Hi coping father - I'm sorry your daughter in this bad relationship. Since you said "should I try to fix it again"...this implies you have tried to help before....is that right? What did you do before? Although I agree with gimmeice, I'm also a parent and I wish when I was younger one of my family members would have convinced me not to get involved with my husband. There were red flags but my emotions wouldn't let be take notice plus I was naive.

I suggest you give her some info on emotionally abusive relationships. This isn't the kind of young man you want your daughter involved with. Sure he's nice sometimes....all abusive men have a charming endearing side - this is how they get women in the first place. Teach your daughter that no friend or partner should ever call her derogatory names or abuse her emotionally. Let her know you will step in if she needs your help, but I pray she cuts him off. This will only end up getting worse and your daughters emotional health is at stake. Here's a good link Sabby put up a while back. Your daughter deserves better but she first needs to get healthy before seeing someone else. This is emotional abuse.

http://www.stanford.edu/group/svab/relationships.shtml