Introduction

While monogamy remains the dominant, ideal type of romantic relationship in Western cultures [1, 2], recent research has found that interest in non-monogamy, notably in polyamory, is on the rise [3, 4]. In response to this growing interest, recent papers have delved deeper into this phenomenon, allowing for more extensive examination and discussion of non-monogamous relationship dynamics and experiences [5–7]. These relationship models are based on the explicit agreement that both partners are free to engage in sexual activity [e.g., open relationships; 4, 8] or in romantic relationships with others [e.g., polyamory; 9, 10]. Recent research in North America suggests that almost 5% of people are currently involved in a non-monogamous relationship [3, 11].

Overall, research suggests that LGBTQ+ persons are more likely to engage in consensually non-monogamous relationships than their heterosexual cisgender counterparts [12–14]. Research has also shown that, among LGBTQ+ individuals, bisexual people are more likely than gay and lesbian individuals to practice non-monogamy [for a review, see 15]. Additionally, recent research has shown that transgender and nonbinary individuals are more likely to be involved in polyamorous relationships than their cisgender counterparts [9, 16, 17]. In a recent U.S. study, 44.6% of bisexual men and 35.0% of bisexual women, compared to 31.6% of gay men and 21.3% of lesbian women reported prior involvement in consensual non-monogamy [3]. According to the same study, 24.6% of heterosexual men and 16.3% of heterosexual women had been in a consensually non-monogamous relationship at some point in their lives. These group differences might be attributable to the fact that, because LGBTQ+ persons are less likely to endorse heteronormative scripts, they are more inclined to consider and explore alternative scripts and relationship configurations [18]. As for bisexual individuals more specifically, Me Lean posits that their greater likelihood of engaging in consensual non-monogamy might be due to the possibility that it allows for the pursuit of sexual and romantic experiences with partners of different genders [2]. Also, another study suggests that the exploration of non-monogamy in and of itself can be an incentive for the exploration of plurisexuality [19].

Because non-monogamous relationship configurations have long been regarded as harmful to both society and individuals [4, 20], researchers have investigated their potential effects on individuals’ psychological and relational well-being [21, 22]. Earlier studies have shown that being in a non-monogamous relationship is associated with poor well-being [23, 24]. By contrast, several recent studies have found that consensually non-monogamous relationships present high levels of sexual satisfaction [1], intimacy, commitment, and relationship satisfaction [25, 26]. Moreover, recent research has shown no differences between non-monogamous and monogamous individuals in terms of psychological and relational well-being [22, 27, 28], life satisfaction [21], and health [29]. It is noteworthy that the studies suggesting negative implications of non-monogamous relationships predominantly stem from research conducted in the 1970s and 1980s, while more contemporary investigations tend to emphasize the positive aspects of such relationships. One of the salient factors contributing to these disparities may be the shifting societal perspectives and attitudes toward non-monogamous relationships over time. Another possible explanation for these conflicting findings is the oversight or neglect of potentially confounding variables that may also impact relationship well-being and satisfaction, such as the legal relationship recognition, and infidelity.

Indeed, legal recognition has been documented as an important correlate of relational happiness and well-being [30, 31]. A large number of studies has documented that married couples report greater levels of overall health, happiness, and well-being than unmarried same-gender [32, 33] and different-gender couples [34–37]. It is possible that the observed differences between monogamous and non-monogamous couples could be attributable to legal recognition. However, the association between marriage and positive relational outcomes may not only be due to civil recognition, but also to what marriage entails, such as the division of domestic labor and childrearing duties, the allocation of family resources, and daily social support, all of which are also relevant to unmarried cohabiting couples [30, 31].

Given that most studies have compared married and unmarried people without accounting for cohabitation, it is difficult to determine whether the documented positive relational outcomes are attributable to relationship status (i.e., being married) or to cohabitation more specifically [30]. Yet, studies having compared married and unmarried cohabiting couples have yielded conflicting results. On the one hand, some studies report that marriage, compared to nonmarital cohabitation, is associated with greater well-being [31, 38, 39] and relationship quality among different-sex couples [40, 41]. On the other hand, other studies did not find any differences between cohabitation and marriage [30, 42] or have found that differences in relational well-being favoring married individuals were attributable to other variables, such as gender roles and social and institutional support for marriage [43, 44].

Infidelity has also been found to be associated with lower relationship quality and psychological well-being [45–47]. Recent studies have found infidelity to be strongly associated with insecure attachment [48], relationship dissatisfaction [49], and poor mental health outcomes [47, 50]. Given that approximately 20 to 25% of people in the U.S. [51] report having engaged in extradyadic sexual activity without their partner’s knowledge or consent, infidelity is an important factor to consider when examining well-being and relationship quality. However, most research typically defines infidelity as engaging in sexual or romantic activities outside of the primary relationship, without considering the importance of relationship agreement [52, 53]. Consequently, many participants in consensually non-monogamous relationships who reported extradyadic sexual or emotional intimacy could be inaccurately labeled as unfaithful in these studies, potentially leading to biased findings. In this context, it is crucial to emphasize that relationship agreement serves as an essential framework for comprehensively understanding the concept of infidelity and its implications within various relational dynamics.

The internet, including dating applications, has also been known to facilitate extradyadic connections and encounters [54–57]. According to U.S. data, 42% of people using dating applications are in a committed relationship [55]. The seeking of sexual or romantic connections online while being partnered could be examined as an indicator of infidelity not only in monogamous relationships, but also in consensually non-monogamous relationships, depending on the specific relationship agreement (e.g., open relationship; polyamory; etc.).

Most studies having examined diverse relationship configurations concurrently with the aforementioned relationship elements have been conducted among gay men [9]. For this study we have selected five relationship indicators available in our dataset. To our knowledge, no study has investigated legal relationship status, cohabitation, relationship agreement, and the use of internet to seek sexual and romantic partner and their association with psychological and relational well-being in a sexually diverse sample. The first aim of the present study was to address this gap and to identify subgroups characterised by similar multidimensional romantic relationship patterns in a large, sexually diverse sample, using a person-centred approach. In addition, some authors have speculated that certain sociodemographic variables, such as sexual orientation, and socioeconomic status can predict one’s propensity to engage in consensually non-monogamous relationships [e.g., 6, 58, 59]. For instance, studies have shown that individuals with higher socioeconomic status are overrepresented in non-monogamous relationships [58, 59]. This overrepresentation may be attributed to financial barriers associated with non-monogamy (e.g., additional costs for travel, activities, and entertainment when dating multiple partners), which can disproportionately impact individuals from marginalized socioeconomic backgrounds.

However, very few studies have assessed the prevalence of these sociodemographic characteristics across relationship configurations. Therefore, the second objective of this study was to explore the relative distribution of these characteristics across various relationship structures. The present study’s third objective was to investigate well-being indicators and perceived partner support across different relationship profiles.

Materials and methods

Participants

A community sample (N = 4,746) completed an online survey as part of the Understanding the Inclusion and Exclusion of LGBTQ People (UNIE-LGBTQ) research project. Eligible participants needed to be able to understand French or English, be at least 18 years old, identify as LGBTQ+, and reside in Quebec (Canada). Participants were recruited via printed media, community partners’ listservs, websites, and social media, and through word of mouth. To address concerns about illegitimate responses and duplicate entries, we implemented several strategies to verify the authenticity of participant data. These strategies included examining the consistency of responses across survey sections, cross-referencing email and IP addresses to identify potential duplicates, and conducting manual reviews of unexpected responses to identify any patterns indicative of illegitimate responses. People who did not provide any information on their relationship status or duration and who were not currently in a relationship were excluded from analyses (n = 2,037). Further, as some of the selected measures used a 12-month timeframe, participants who had been in a relationship for less than one year were also excluded (n = 367). The analytical sample (n = 1,528) only included participants who provided complete data on the five latent profile indicators (excluding 814 more cases). See Table 1 for the sample’s demographic characteristics.

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Table 1. Sample characteristics.

https://doi.org/10.1371/journal.pone.0309954.t001

Results

Latent classes

A five-class solution was identified as the optimal model (see Table 2). The indicators’ conditional probabilities for each class are presented in Table 3. Class 1 (59%; formalized monogamy) includes participants in legally recognized unions (married, civil union, or common-law) with a monogamous agreement, who are cohabiting, and who had never or rarely used the internet to seek another sexual or romantic partner in the last year. Class 2 (20%; free monogamy) was composed of participants in relationships that were not legally recognized, who had a monogamous agreement, who were not cohabiting, and who had never or almost never used the internet to seek another sexual or romantic partner in the last year. Class 3 (7%; monogamous considering alternatives) included participants who were monogamous and cohabiting and had used the internet once or a few times over the previous year to seek sexual and romantic partners. Class 4 (11%; formalized open relationship) described participants who were in open, cohabiting, and legally recognized unions, and who used the internet once a month or more often to find sexual, but not romantic partners, in the last year. Class 5 (3%; free consensual non-monogamies) was the smallest and included participants who were in open relationships that had not been formalized, and who had used the internet once a month or more often in the past year to look for other sexual and romantic partners.

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Table 2. Goodness of fit indices of LCA models.

https://doi.org/10.1371/journal.pone.0309954.t002

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Table 3. Class description across relationship indicators.

https://doi.org/10.1371/journal.pone.0309954.t003

Class differences on sociodemographic characteristics

Table 4 shows the five latent classes’ sociodemographic composition. Bonferroni-corrected pairwise comparisons revealed that participants in the free monogamy class were younger than those in formalized monogamy and formalized open relationship classes (all p < .001). As age is a potential confounder for most sociodemographic variables [75, 76], all subsequent Wald tests and corresponding p-values were computed on age-adjusted proportions. The free monogamy, monogamous considering alternatives and free consensual non-monogamies classes reported lower relationship durations than those in other classes (all p < .001). The formalized monogamy and formalized open relationship classes reported higher household incomes (> $99,000 CAD) than the other classes (all p < .001).

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Table 4. Sociodemographic composition of latent classes.

https://doi.org/10.1371/journal.pone.0309954.t004

Bonferroni-corrected between-class comparisons also revealed that cisgender men were overrepresented in the formalized open relationship (72%) and free consensual non-monogamies (68%) classes and underrepresented in the formalized monogamy (33%) and free monogamy (38%) classes. Conversely, cisgender women were significantly more likely to belong to the formalized monogamy (55%) and free monogamy (52%) classes than to any other class (all p < .001). While nonbinary individuals predominantly belonged to the monogamous considering alternatives and formalized open relationship classes, the prevalence of nonbinary persons in the remaining classes were not statistically different from one another, likely due to limited statistical power afforded by the small subsample of nonbinary individuals. Regarding partner gender, unadjusted results indicate that individuals in the monogamous considering alternatives, formalized open relationship, and free consensual non-monogamies classes were more likely to be paired with multiple genders (all p < .05). However, the Bonferroni-corrected post-hoc comparisons yielded nonsignificant results.

Class differences on well-being and social provisions from partner

Table 5 shows between-class differences on well-being and social provisions from a relationship partner. After adjusting the models for potential confounders (age, gender modality and identity, education, partner gender, and relationship duration), participants in the formalized monogamy class reported higher levels of social and emotional well-being than those in the formalized open relationship class. No other class differences on well-being indicators were found. Regarding social provision indicators, individuals in the free monogamy class indicated lower levels of reliable alliance, guidance, and social integration compared to those in the formalized monogamy class. Similarly, the free consensual non-monogamies class reported lower levels of guidance and attachment from their relationship partners than individuals in the formalized monogamy class.

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Table 5. Class differences on well-being indicators and social provisions from relationship partner.

https://doi.org/10.1371/journal.pone.0309954.t005

Discussion

This research used LCA to investigate relationship structure patterns and their correlates among LGBTQ+ individuals in Canada. Five latent classes were identified. Two classes were composed of participants in a monogamous relationship: those who were legally married and cohabiting (formalized monogamy; 59%), and those who were legally single and non-cohabiting (free monogamy; 20%). The three other classes were participants with non-monogamous practices. One class was composed of cohabiting participants with a monogamous relationship agreement who sought outside sexual and/or romantic partners on the internet once or a few times a year (monogamous considering alternatives; 7%). The other two classes were composed of consensual monogamous participants: those in a legally recognized relationship with a non-monogamous relationship agreement who cohabit and who often seek outside sexual partners on the internet (formalized open relationship; 11%), and those who are legally single with a non-monogamous relationship agreement, who do not live with their partner, and who often seek outside sexual and/or romantic partners (free consensual non-monogamies; 3%).

The proportion of participants involved in consensual non-monogamy in the overall sample (14% open relationship; 3% polyamorous) was greater than that reported in previous studies [3, 10], likely reflecting the absence of cisheterosexual persons in the present sample. As suggested by Rutherford et al., LGBTQ+ persons’ non-normative sexuality and gender expression may provide a context that is conducive to the development of non-normative relationship configurations in which sexual and affective exclusivity are negotiated rather than assumed [17].

Sociodemographic differences were found between classes. First, congruently with previous research [8, 11, 25, 77, 78], the present study showed that cisgender sexual minority women were more likely than cisgender sexual minority men to engage in monogamous relationships, and the latter were more likely than the former to be in open relationships. Some studies suggest that lesbian women may have a greater adhesion to heteronormative gender roles prescribing monogamy, marriage, and family [79, 80] than do gay men. This discrepancy may be attributed to apprehensions linked to sexual double-standards and the societal censure that women might encounter when articulating their sexual inclinations and preferences within consensually non-monogamous relationships [52]. In contrast, gay men have been found to be more resistant to heteronormative sexuality, allowing them to more freely embrace diverging relationship ideals and configurations or to resist those that are socially enforced [81]. Some evolutionary psychology hypotheses suggest the existence of sex differences in mating strategies, with cisgender women being more likely to endorse monogamy, and cisgender men, non-monogamy [82, 83].

Contrary to previous findings [58, 59], we did not find white and higher household income participants to be overrepresented in non-monogamous classes. In the present sample, the free monogamy class was comprised of individuals reporting lower household income, which may reflect the overrepresentation of younger participants in this class. The fact that these individuals generally have lower personal incomes and are less likely to cohabitate with their partners can negatively affect their household income.

Further, in the present study, educational attainment was not significantly associated with class membership. Research having examined this question presents conflicting findings, with some studies suggesting lower levels of education among individuals engaged in non-monogamous relationships [84], and others reporting greater proportions of highly educated individuals among non-monogamous participants [59]. These inconsistencies suggest the involvement of other unmeasured variables and underscore the need for further investigation.

The present study also found that participants in the free consensual non-monogamies class reported lower levels of emotional and social well-being than those in the formalized monogamy class. Similarly, individuals who were legally single (i.e., free monogamy and free consensual non-monogamies) reported lower overall levels of perceived partner support than those in the formalized monogamy class. Such group differences could be attributable to several factors. First, choosing or intending to have one’s relationship legally recognized might reflect preexisting relationship characteristics, such as greater levels of satisfaction [85] or mutual support. Second, between-group differences in perceived partner support may be indicative of relational marginalization, that is, the stigmatization of same-sex unions at the family, community, and societal levels and its detrimental impact on such relationships [86, 87]. While legal recognition can provide some validation to same-sex unions, its absence might lead to further marginalization or stigmatization, which are known to negatively affect relationship functioning [88].

A third possible explanation for the low levels of perceived partner support within the free consensual non-monogamies class is the possibility that some individuals in the former group were in a transitional stage toward an open relationship. Many non-monogamous relationships were initially monogamous, and the process of negotiating rules and setting boundaries, as well as the trials and errors that many partners engage in when first practicing non-monogamy can create a context that fosters relationship instability, which could feed into perceptions of lower partner support.

Finally, it is also possible that some participants in the free consensual non-monogamies class reluctantly consented to a non-monogamy agreement or were otherwise dissatisfied with their relationship agreement. One recent study suggest that non-monogamous relationships characterized by lower levels of mutual consent and comfort regarding their relationship agreement demonstrated the lowest levels of individual and relationship functioning [89]. Future non-monogamy research examining well-being and relationship quality should account for relationship stage (i.e., transitional/negotiation stage) as well as consent and comfort vis-à-vis relationship agreement.

The absence of significant group differences on well-being indicators is inconsistent with studies that have documented poorer well-being among individuals in non-monogamous relationships [23, 24]. However, this finding aligns with research showing no differences between monogamous and non-monogamous individuals regarding well-being [22, 27], life satisfaction [21], health, and happiness [29]. Some studies also suggest that compersion—the positive attitudes, thoughts, and actions that arise in response to one’s intimate partner’s extradyadic intimate relationships [90]—significantly correlates with relationship satisfaction in consensually non-monogamous relationships [90–92]. As Rubel and Bogaert hypothesized, it might not be the adhesion to non-traditional relationships per se that predicts negative outcomes, but intra-relational characteristics that go beyond sexual and romantic exclusivity [22].

Conclusion

The present study explored various relationship structures among LGBTQ+ individuals in Quebec (Canada), identifying five distinct patterns ranging from formalized monogamy to non-monogamous agreements. The prevalence of non-monogamous relationships in this sample exceeded previous estimates, reflecting the unique sociocultural context of LGBTQ+ individuals. Gender played a significant role, with cisgender women more inclined towards monogamy, while cisgender men leaned towards non-monogamy, challenging conventional assumptions. The study also revealed disparities in perceived partner support across different relationship classes, potentially linked to factors such as the cultural significance of marriage, internalized sexual stigma, and relationship stage (e.g., pre-, post-, or during transition from monogamy to consensual non-monogamy). However, no significant differences were found in well-being between monogamous and non-monogamous individuals, suggesting that relationship dynamics may be a more important factor than relationship agreement per se. This study offers valuable insight into the diverse landscape of LGBTQ+ relationships in Canada, emphasizing the need for nuanced exploration of the factors shaping these relationships, with implications for research and support services within the LGBQ+ community. Understanding this complexity is also essential for creating healthier, more inclusive, and supportive environments for relationship diversity among LGBQ+ communities.

Acknowledgments

The Understanding the Inclusion and Exclusion of LGBTQ People research (UNIE-LGBTQ) is a research partnership of universities, public agencies, semi-public and community-based organizations, and private enterprises dedicating their efforts to better understand situations in which LGBTQ + people are demeaned, rejected, and belittled, and deprived of the full extent of their rights in important life domains. The authors extend their gratitude to their research partners as well as to the participants who generously shared their experiences with them.