Why are people sometimes mean to people they like?

Its far more common with pre-teens and adolescents, I think. But even since I’ve been an adult, I’ve had a few experiences with “mean girls” who turned out kind of liked me. It has been over twenty years, but I still wonder about the phenomenon.

I am NOT referring to the separate issue of what we hurt people we love or who love us most.

I am referring to those crushes we had earlier in life and co-workers I had, in my first and second job I myself was never mean to anyone I liked. After all, I wanted them to “like” me so I myself was inclined to shower them with kindness.