London - Having a great sex life with your spouse is normally seen as a good reason to stay faithful.
However, a husband’s or wife’s prowess could actually make their bedmate more – not less – likely to stray.
This is because those who really enjoy sex in a marriage may then want to seek out liaisons with more partners, according to researchers.
They also found that attractive women were slightly more likely to remain faithful than their less attractive peers.
In contrast, a man who was more attractive was more likely to stray.
The findings came in a wide-ranging study at Florida State University examining if it was possible to predict if someone was likely to cheat in a relationship.
They found that those whose gaze lingers on attractive "alternative" mates were the ones who would be more likely to cheat and their marriages to fail.
Researchers followed 233 newlywed couples for up to three-and-a-half years, documenting intimate details, including marital satisfaction, long-term commitment and infidelity.
"Sexual satisfaction was surprisingly positively associated with infidelity," they wrote. "It may be that people who feel particularly positive about sex in general, regardless of how they feel about their relationships specifically, are more likely to engage in an infidelity."
The authors said satisfaction with sex was separate to being happy with the relationship in general. Overall satisfaction with their marriage made people less likely to have affairs.
But the authors said their research showed you could be happy with your sex life but dissatisfied with the relationship in general.
In the project, they also asked participants to look at photos of other people and evaluate their attractiveness.
Their report in the Journal of Personality and Social Psychology found that faithful partners gave lower scores than those who went on to cheat.
The "increased availability of and access to alternative partners" on social media made it more relevant than ever to understand how people avoid temptation, added the academics.