Perhaps I'm just old fashioned, but whenever I see a phrase like "had given her bruises while they were fighting last night" it's my sense that the relationship should end immediately.
Abuse is serious stuff. Although they may not be willing to break out of this senseless cycle, a responsible adult must intervene. It's that, or risk this pattern of behavior escalating.
I apologize for preaching, but I feel very strongly about this. Again, this is hitting we're talking about.