Wondering if your spouse is cheating on you? Check to see how comfortable they are with sex, or how happy they are in the relationship.

A new study performed by researchers at the University of Guelph in Ontario, Canada, and at Indiana University is the first to consider not only demographic information when it comes to determining infidelity, but interpersonal factors and sexual personality as well. When it comes to a cheating spouse, several issues can come into play.

“This research shows that demographic variables may not influence decision-making as much as previously thought — that personality matters more, especially for men,” said Robin Milhausen, a professor and sexuality researcher in Guelph’s Department of Family Relations and Applied Nutrition who conducted the study with Kristen Mark and Erick Janssen of Indiana University.

The study involved 506 men and 412 women. All participants in the study reported being in monogamous relationships lasting from three months to 43 years. They also provided basic demographic information, including income, religion and education.

The participants also completed scales that measured their sexual personality variables as well as answered questions about their relationships.

While there was little difference between the sexes in the rates of infidelity – 23 percent for men, 19 percent for women – the reasons for why they cheated varied.

For men, the driving causes behind infidelity included ease of sexual excitement and concern about sexual performance failure.

The latter might seem like an odd reason to cheat on a partner, but as Milhausen explains, “People might seek out high-risk situations to help them become aroused, or they might choose to have sex with a partner outside of their regular relationship because they feel they have an ‘out’ if the encounter doesn’t go well – they don’t have to see them again.”

For women, the primary reason for committing infidelity was unhappiness in the relationship. Such women were twice as likely to cheat, and women who felt sexually incompatible with their partners were three times as likely.

“For women, in the face of all other variables, it’s still the relationship that is the most important predictor,” said Milhausen.

While Milhausen warns that the study should not be used to support sexual stereotypes, she does say that these personality traits are useful for determining potential actions and will allow couples to seek therapeutic solutions.

This study appears in the journal Archives of Sexual Behaviour.