Consensual non-monogamy is routinely framed as a riskier bargain than monogamy, one that trades stability for excitement at the expense of a satisfying sex life. Two studies out of the University of Turku’s INVEST Research Flagship Centre in Finland, covering a combined 888 adults in an initial convenience sample and a population-based dataset of 10,503 Finnish adults, found the opposite. According to reporting on the findings, people with multiple partners reported sexual functioning that matched, and in some measures slightly exceeded, that of monogamous respondents. Women with multiple partners reported greater desire and arousal with non-primary partners than with primary ones. Non-monogamous men reported fewer premature ejaculation symptoms than monogamous men did.
The Surprising Data on Infidelity and Health Outcomes
Perhaps the most counterintuitive finding involved infidelity itself. Across both the convenience sample and the much larger population-based Finnish dataset, infidelity showed minimal negative association with sexual health outcomes, a result the research team reportedly did not expect going in. Both consensually non-monogamous and monogamous respondents in the study reported slightly elevated dyadic desire, meaning desire for one’s actual partner rather than a hypothetical one, suggesting that having an arrangement built around honesty about multiple partners doesn’t erode desire for any one of them. None of this suggests infidelity is harmless to a relationship’s trust or stability. It suggests that its effects on sexual functioning specifically are smaller and more complicated than assumed.
More Testing, Not More Infections
One place non-monogamous respondents did stand out was in sexual health screening habits. People in consensually non-monogamous arrangements were 3.6 times more likely to get tested for sexually transmitted infections than monogamous respondents, according to the Turku findings, yet their actual infection rates matched the monogamous population rather than exceeding it. That combination, more testing paired with equivalent infection rates, points to a group that is managing risk actively rather than a group that is simply exposed to more of it. It undercuts one of the more persistent assumptions about open relationships: that more partners automatically means worse sexual health outcomes for everyone involved.
A Much Larger Study Backs This Up
The Turku research isn’t an outlier finding. A meta-analysis led by Associate Professor Joel Anderson of La Trobe University’s Australian Research Centre in Sex Health and Society, published in the Journal of Sex Research and announced via EurekAlert, pooled data from 35 separate studies and 24,489 participants across the United States, Canada, Australia, Portugal, Italy, and other countries. That analysis found monogamous and non-monogamous people reported similar levels of both relationship satisfaction and sexual satisfaction, with no significant differences showing up across LGBTQ+ and heterosexual participants, or across different non-monogamous structures like open relationships and polyamory. Two research teams working independently, using very different methods and populations, landed on the same basic conclusion: the sexual and relational cost of non-monogamy has been overstated.
Why the Sample Size Actually Matters Here
A lot of relationship research relies on small, self-selected convenience samples, often recruited from university psychology pools or online forums for people already interested in the topic being studied, which makes it hard to know whether findings generalize to anyone outside that narrow group. The Turku researchers avoided that trap by pairing their initial 888-person convenience sample with a genuinely population-based dataset of over 10,500 Finnish adults, the kind of large, broadly representative sample that is expensive and logistically difficult to assemble. When a convenience sample and a population-based sample point in the same direction, researchers treat that as considerably stronger evidence than either one would provide alone. It’s part of why this particular finding has attracted more attention than the average relationship study: the size and design make it much harder to dismiss as a fluke of who happened to answer the survey.
Why the Old Assumption Persists Anyway
Part of why “non-monogamy wrecks your sex life” still feels like common sense is that most cultural messaging about relationships treats monogamy as the neutral default and everything else as a deviation requiring justification. Population-level data doesn’t work that way. It just measures what’s actually happening inside tens of thousands of real relationships, and what it shows is a much smaller gap between the two arrangements than the conventional wisdom suggests. People choosing structured non-monogamy aren’t gambling with their sexual health in some obvious, measurable way; they appear, on average, to be managing it about as well as anyone else, and in the case of STI testing, arguably better.
