There’s always that one friend—you know the type—there when she wants to be, supportive but not too supportive, flaky, and seems like she only wants to be your friend when it’s convenient for her.

It’s the type of friendship you probably first encountered as an adolescent, but never seems to go away even into adulthood. You might find yourself asking why you stay friends with her in the first place, and, while it seems like more energy than it’s worth sometimes, there is some light at the end of the tunnel.

She can teach out a lot about the friend you don’t want to be.

If you’ve ever flaked on plans with a longtime friend, or have ended up talking negatively about a friend to someone else, you know the feeling that comes from these decisions. It doesn’t feel good, and can build up a lot of guilt. Similarly, because of your frenemy, you know how it feels to be on the receiving end. The next time you go to cancel plans at the last minute or engage in otherwise unfriendly behavior toward someone you really cherish, think about how it hurts to have this happen to you.

She can make you more self-aware.

It’s one thing to be genuinely mean to someone (e.g. commenting on someone’s weight, calling them names, etc.), which is never OK, and another to be constructive as a friend. Friendship is about honesty, and you likely expect a friend to be upfront with you in a way other people just can’t. A frenemy is more likely to be honest with you in a way that is less constructive and more deprecating (likely because of her own insecurities). Remember how unproductive these harsh critiques can be, and how useful positive honesty can be.

She can help you love yourself.

If you’ve ever watched someone be a complete jerk to a server, or a driver cut someone off in traffic, it can help you think about how nice a person you are and how you treat people. When a friend is ugly toward you, it may sting, but it also makes you aware of just how good you are.

She can put things into perspective.

The feeling you get spending time with your really good friends is a feeling you wish you could have all the time. Unfortunately, as adults, we all have lives of our own and can’t spend every moment with those we love. And when you spend time with a friend who you aren’t as close with, it can really help you appreciate the great support system you do have in your closest friends.

If you’re having difficulties with a frenemy, don’t blame yourself. Look at it as a learning experience, and use your feelings to better your other relationships.