Healthy Me

My little sister is trying to get engaged. I say "trying" because her boyfriend wants to but my sister seems to have these phobias about men who treat her too nicely. I'm not sure why she always picks guys who treat her badly and then wants to run from the good guys who are nice. She's definitely never been without a guy - - not a candidate for free online dating but she goes from nice to bad to nice to bad. I am hoping she'll finally get engaged to the current boyfriend and not get scared and sabotage it.

Why do women do that?