Tom Hanks, earnest and endearing, finds love in "Sleepless in Seattle." Hugh Grant, bumbling yet charming, ends up with Andie MacDowell in "Four Weddings and a Funeral." Even the supposedly cynical Harry wins Sally with a well-timed display of vulnerability.

But while nice guys win hearts on the silver screen, a study suggests they may struggle in the unforgiving arena of real dating.

The findings, published in the Journal of Research in Personality, indicate that personality traits are linked to relationship success in markedly different ways for men and women.

The authors sent questionnaires to 3,800 adults in Australia, Denmark and Sweden to assess their personalities. They were asked whether they were in a relationship and, if so, how satisfied they were with it.

When it came to kindness, there was a divide between the sexes. Women who were more “agreeable” — meaning empathetic, co-operative and patient — were no more likely to be in a relationship than women in whom these qualities were less pronounced.

For men, though, agreeableness seemed to work against them. The correlation between kindness and being in a relationship was weak but slightly negative. In other words: the nicer he was, the less likely he was to have a partner.

The researchers also found that men who were more outgoing, confident and sociable were significantly more likely to be in a relationship, compared with less extroverted men.

For women, by contrast, being extroverted made little difference: outgoing or shy, their chances of having a partner were roughly the same.

Finally, men who tended to worry or feel anxious, displaying what psychologists call neuroticism, were less likely to have a partner. Among women, the same trait was linked to a different outcome: those who scored higher on neuroticism were slightly more likely to be in a relationship.

The authors speculate that the results may reflect the persistence of traditional stereotypes and expectations. Confidence and autonomy may still be thought of as attractive in men; empathy and emotional warmth remain more desirable in women.

Filip Fors Connolly, an associate professor of sociology and psychology at Umea University in Sweden, who led the research, said: “An assertive, extroverted man may get positive responses when approaching potential partners, while an assertive woman might face ambivalence or negativity. A man expressing anxiety might be seen as socially weak, while for women it’s more acceptable.”

Mikael Goossen, also of Umea University, added: “The implication is that even in progressive societies, people whose personalities don’t conform to gender stereotypes face barriers in forming relationships, potentially forcing them to choose between authenticity and romantic success.”

There was, however, a distinction between entering a relationship and maintaining one. “Agreeable men were less likely to have a partner. However, this doesn’t mean agreeableness is bad for men’s actual relationships,” said Connolly.

In fact, being kind and patient increased the likelihood that both men and women would be pleased with their relationship, were they in one. “The traits that help you get into a relationship aren’t necessarily what make it satisfying,” he said.

He cautioned those seeking love against reading too much into the findings: “Our focus is on common patterns across thousands of people. None of this determines any single person’s relationships or their quality.”

This article originally appeared on TheTimes.com.