He has a close female friend. Is that a problem?

After 40, the person you’re dating arrives with friendships that predate you, sometimes by decades. Some of those friends will be of the opposite sex. You didn’t choose her. She’s part of the package.

That doesn’t make the feeling go away. So here’s what’s known, and what isn’t.

Most of these friendships are just friendships

In a 2000 study of 231 people, the most common kind of attraction in cross-sex friendships was simply liking the person as a friend. Romantic attraction was the least common.2

But attraction isn’t zero, and it isn’t harmless

A 2012 study is the one to know. Researchers asked emerging adults and middle-aged adults about their cross-sex friends. Both groups named attraction to the friend as a cost of the friendship more often than as a benefit. And middle-aged people who felt more attraction to a current cross-sex friend reported less satisfaction with their romantic relationship.1

That’s a correlation. It doesn’t say the friendship caused the dissatisfaction, and it could easily run the other way. It does say the question you’re asking isn’t silly.

Your jealousy may be about something else

Two findings put a different light on the feeling.

First, in a 2019 survey of 346 people, those who were engaged had the most negative views of cross-sex best friendships, more than people who were single, dating or married.3 Where you are in the relationship shapes how threatening the friend looks.

Second, a 2014 study found people felt jealous of a partner’s same-sex friends too, especially when the partner was central to their lives and they had doubts about the partner’s commitment.4 The researchers’ reading: the threat isn’t only sexual. It’s about losing your place as the person they turn to first.

So ask yourself which it is. Are you worried about an affair? Or about not being the first call?

Questions that work better than “is it okay?”

• “What does she give you that I don’t, and is there something there for us?”
• “Would you be comfortable with me seeing her messages if I asked?” (Not to read them. To hear the answer.)
• “Can I get to know her better?”

The last one matters. A friendship you’re part of looks very different from one you’re kept outside of.

If jealousy has been showing up across a lot of situations, not just this one, our piece on how to stop being jealous goes further.

What these studies can’t tell you

They surveyed groups at one point in time and asked people to report on themselves.23 None of them can tell you what’s happening in your partner’s particular friendship. They can tell you the worry is common, the risk isn’t imaginary, and the feeling is often about your place in the relationship as much as about her.