Do you have problems with friends being nice to your enemies?

[Foxtail]

Do you have problems with friends socializing or being friendly to your enemies? I have this one friend who is very bad about this she will talk to people she knows and is very social paying little attention to whether this person has been hateful to me. I find this behavior particularly offensive. Sometimes she will even look for them at a store they work at just to talk to them. Also I have coworkers who friend people on social media who aren't very nice to me. Have you deal with friends socializing and interacting with your enemies? How did you feel about it and deal with this?