A pair of studies published in the Journal of Social and Personal Relationships suggests that having multiple romantic or sexual partners does not compromise sexual health. Led by Michelle Larva-Ruhala, a doctoral researcher at the University of Turku’s INVEST Research Flagship Centre in Finland, the research draws on two large datasets and finds that people in consensual non-monogamous relationships, including polyamory or open arrangements, report sexual functioning, satisfaction, and health outcomes that are comparable to, and in some cases slightly better than, those in strictly monogamous partnerships. The work distinguishes between consensual non-monogamy and secrecy or infidelity.
Consensual non-monogamy involves partners mutually agreeing to outside romantic or sexual relationships, such as in polyamory or open relationships. Infidelity, by contrast, involves outside encounters conducted secretly and without a partner’s consent.
It is common to assume monogamy is inherently safer and more satisfying, but prior research has offered a more nuanced view. For example, earlier studies noted that consensually non-monogamous individuals often report similar relationship quality and sexual satisfaction to monogamous couples, while other work suggested different patterns in sexual health and safety. The current study builds on this progression by testing whether sexual functioning, desire, and STI risk actually differ across relationship types, strictly separating consensual non-monogamy from non-consensual infidelity.
The researchers used a two-study approach. In Study 1, data from 888 adults recruited through an online survey across the United States, Portugal, Italy and Finland were analysed. Participants reported whether they identified as monogamous or consensually non-monogamous, with categories including polyamory and open relationships, and whether their interactions with others felt like infidelity or involved keeping sexual and emotional secrets from a primary partner.
To measure sexual functioning, the survey employed validated questionnaires assessing domains such as desire, arousal, lubrication and satisfaction for women, and erection, ejaculation and satisfaction for men. Participants with multiple partners answered these measures for up to two partners. The survey also collected information on participants’ history of testing for and diagnoses of sexually transmitted infections.
The results of Study 1 showed that sexual functioning was largely similar between monogamous and non-monogamous individuals. However, there were partner-specific differences. Women with multiple partners reported greater sexual desire, arousal and satisfaction with their non-primary partners compared with their primary partners, and their scores with non-primary partners were higher than those reported by single-partnered women.
These findings echo prior research indicating enhanced erotic experiences with secondary partners among polyamorous individuals, while among men, sexual functioning did not vary by relationship type or partner.
When it came to sexual health practices, polyamorous individuals were 3.6 times more likely to have ever been tested for a sexually transmitted infection than monogamous individuals. Despite this higher testing rate and having more partners, the prevalence of STI diagnoses did not differ between the groups.
For the most part, infidelity was not linked to worse sexual functioning. There was one exception: men who reported keeping emotional attachments and sexual encounters secret from their primary partner tended to report lower sexual satisfaction in that primary relationship.
“We were surprised by the finding that infidelity was not associated with worse outcomes,” Larva-Ruhala noted. “Both studies suggest that, on average, having multiple concurrent partners isn’t necessarily tied to poorer sexual health, whether through consensual or non-consensual non-monogamy.”
The second study expanded the investigation to a population level, using a pooled dataset of 10,503 participants from Finland. This dataset combined responses from genetic and behavioural research projects. Participants self-reported their relationship structure and completed broad measures of sexual wellbeing, including women’s overall sexual desire and functioning and men’s premature ejaculatory symptoms, as well as general dyadic desire for an attractive partner.
To ensure fair comparisons between the small proportion of non-monogamous individuals and the large monogamous majority, researchers statistically matched participants on age, gender, and sociosexual orientation, a measure of willingness to engage in uncommitted sex. They also controlled for cohabitation and the gender of partners.
This approach offered a key advantage. “The method used in Study 2 is important for the current research on [consensual non-monogamy],” Larva-Ruhala explained. “Most studies… use data collected from online surveys that people in [consensually non-monogamous] relationships opt into, which is partly necessary in order to obtain a big enough pool of participants to conduct the analyses we want to do, but it also means heavy selection-bias.”
“People who are generally happy in their relationships and interested in representing their relationship configuration may be more quick to participate in these surveys,” she added. “However, study 2 used data from population-representative samples in studies not focused on [consensual non-monogamy], so we can assume people all across the board completed the survey, lowering some of that bias. It improves the generalizability of the results.”
In this population-based sample, non-monogamous men reported fewer early ejaculatory symptoms than their monogamous counterparts. Non-monogamous women reported higher global sexual desire than monogamous women, and both men and women in non-monogamous relationships reported slightly higher dyadic desire.
Again, when researchers isolated the effects of infidelity—defined here as cheating or partners who were unaware and non-consenting—they found no effect on these sexual health outcomes. This broader lack of negative effects aligns with a major review covered earlier this year, which found consensually non-monogamous individuals report levels of relationship and sexual satisfaction indistinguishable from those of monogamous couples.
As with all research, there are limitations. The studies relied on self-reported measures of sexual functioning and health, which can differ from objective physiological indicators or medical records. Participants might misremember STI histories or tailor responses to appear more favourable. In Study 1, some participants were grouped under non-monogamy without distinguishing the specific agreements they had with their partners, such as cohabitation or relationship hierarchies. In Study 2, the infidelity measure combined current and past cheating, potentially diluting its measurable impact on current sexual health. Future work could track couples over time to see how relationship agreements evolve.
“Just because we didn’t find many differences in sexual health between those who cheat and those who practice ‘ethical’ forms of non-monogamy, doesn’t mean that doing one or the other is of no consequence,” Larva-Ruhala emphasised. “The results certainly don’t condone infidelity. They simply show that people can maintain sexual health under both versions of non-monogamy.”
The researchers hope to see replication of these findings through further evidence, ideally in population-based samples from other countries. The study is titled “Sexual Health in Monogamous and Non-Monogamous Relationships: Evidence From Convenience and Population-Based Samples,” and was authored by Michelle A. Larva, David L. Rodrigues, Annika Gunst, Patrick Jern, Sabina Nickull, Marie-Pier Larose, Markus J. Rantala, and Justin K. Mogilski.
