My advice: Don't get involved. If you want to listen to her complain, knock yourself out. But don't try to "save her"! Never, ever get involved in others' domestic situations, it's always a trap.

The sad truth is that girls who stay in abusive relationships have problems of their own that make them keep going back. They need professional help, not comforting. Getting yourself sucked into an unhealthy relationship doesn't help anyone.