While I agree magick does not solve every issue in life, I like your ideas as to what sort of spell you are looking for and think it would actually be beneficial.
I would suggest making one to help her see her own self worth. In abusive relationships, the victim tends to not have any self worth left, it is part of a process (that could have even begun before the boyfriend showed up) in which the person needs to be broken down mentally. Many times they make excuses for their abuser or see it as something they "deserve". In truth, not many people have the courage or strength to leave the relationship.
Assuming you know about magick and spell casting to begin with, I would strongly encourage a self written one (as the emotions you pour into it will be more direct than a spell by anyone else) for courage and self worth. The best you can do other than that is to be her support system.