What can you tell an anarcho-communist who gives lectures about the oppressive capitalist system and all its coercive institutions yet he beats his girlfriend, fractures her nose, sends her to er, and then coerces, convinces her to trust him again, and again, and again? Of course, she is in such awe of his politics that she will not call the cops on him. What to do? The girl is my daughter!!!!!! help!!!!!
one other thing. it might be possible to talk to her about caring about him and his ability to be in intimate relationships without hurting people. ie, it is possible that if he agrees he doesn't want to be treating people this way, then perhaps he could be in therapy (not with her, probably, but on his own), and that would make his life significantly better as well as hers. so she would be expressing her concern for him through working on this with him.
if your daughter sees that as a reality, then that might resolve some issues.
but it is also possible that she doesn't see their fights as a problem. she might -- for example -- appreciate the clarity of physical fights.
very hard to understand these things from the outside sometimes.