There's a psychology to it. She has low self esteem. He still has a control over her. It's hard to describe it to someone who's never been there (and I hope you never are). It's stupid to go back, especially after getting out. But her reasons for it are probably stronger than she feels at the time. Sucks. The only one that can help her at this point, is her.
Details are irrelevant.... she's just dumb.
She isn't strong enough yet to believe she is worth more than that type of treatment. The best thing you can do for her is to help her see how much she has to offer and how much she is valued. When she finally believes in herself - she'll leave him so fast it will make his head spin. The absolute worst thing you can do right now is to tell her how bad he is and how you don't like him - she'll tell him and he'll use that against you - filling her head with lies about how no one but him loves and understands her and how her friends can't be trusted. Believe me.
Or the drugs?
an abuser will cripple you ego making you think that no one else will want you. consequently when you leave one you don't think there will be another option, it's them or nothing. this is one of their most effective tools. the best thing you can do is work on her confidence. also get her to research the psychology involved. there are free websites with advice by type that are quite helpful.
Because she has not come to her senses Yet...???
Love is blind.
oh that is too bad! but she sound so insecure, but she will eventually come to her senses,albeit late in the relationship but she will, so don't say anything to her, she won't listen, but be a friend and be there when she does
I'd look into her relationship with daddy
maybe shes a masochist
masochist will do Fed up things to get punished
girls like bad boys
Maybe she's an addict and he's a dealer...