Think your wife is your best friend? You’re wrong. It doesn’t mean your marriage isn’t wonderful — it’s just a recognition that friendship and marriage, while they share key areas of overlap, are fundamentally different relationships. Experts warn that conflating the two can cause far more problems for your marriage than your friendships.

“In most cases our friends do not live with us, are not financially, legally, relationally entwined with us. Our friends are attached to us because they want to, when they want to,” says marriage and family therapist Carrie Krawiec of the Birmingham Maple Clinic. “They have volition and empowerment to leave or at least take space from us when necessary. Our partners are connected to our homes, family, schedules, life.”

It makes sense that marriage and friendship might be conflated. It’s well-documented that marriage is good for individual health, well-being, and longevity, and the same is true for friendship. Married people also tend to rely less on friendships than single people do. But that’s not because their spouses have stepped into the best friend role — it’s because everyone else has.

“When married, you also have each other’s parents and siblings as sources of support — or even children,” Krawiec explains. “Married people tend to have a broader pool of potential supports.”

However, that’s different from friendship, and mistaking one for the other can cause conflicts in marriages, Krawiec warns. Unreasonable expectations are dangerous things. Husbands who expect their wives to be their best friends may develop impractical expectations of how they should support them and their decisions. If a man were to quit his job to pursue a passion for carpentry, a friend could easily be his cheerleader. But his wife? She’s going to have questions.

“When we mistake our partner’s own questions, fears, concerns as a lack of support, we are holding them accountable to a friend standard that does not exist for our partner,” Krawiec says. “When we get too disappointed or resentful we end up eroding our relationships.”

It’s important to note that mistaking friendship for marriage won’t always harm your well-being. One study found that men who reported that their spouses were their best friends were twice as likely to report high life satisfaction. John Helliwell, a professor at the Vancouver School of Economics who conducted the research, told the New York Timesthat this is likely because men tend to have fewer friends.

And for people who don’t have a lot of friends, let alone a best friend, a spouse becomes more important for their health because that role may not have otherwise been filled. “That’s how we got to the idea that marriage is a kind of ‘super-friendship,’” Helliwell says.

But, still, it’s not a true friendship, and keeping that in mind could be the difference between a successful marriage and a life full of disappointment. If it helps to think of your spouse as a best friend who happens to be financially and legally tied to you, go for it. But keep in mind that, when you heap best-bud expectations onto your wife, nobody benefits.

This article was originally published on Dec. 10, 2018