I think you would benefit from learning about codependency and how to recognize how you end up in that role unknowingly. Often someone is expected to be that way in their childhood and they begin to put other's needs before their own needs. This ends up exposing you to "needy" people or people that suck you into their constant drama that THEY need to learn how to fix themselves and some never do and instead end up repeating the kind of pattern your friend keeps repeating. Yes, your friend does keep ending up repeating dysfunctional patterns in her relationship. YOU can't fix that and it sounds like you are constantly being drawn into this friend's ongoing drama of dysfunction which deprives you of having your own life. Well, that is codependency.