Sh*t, I had a whole long reply and it got lost. I'll try to summarize....
Hope it's OK to add the female perspective. Logic would seem to say that she would ditch the loser and be with the guy who is loving and respectful. Unfortunately, neither men nor women can be accused of logic when it comes to matters of the heart.
I volunteered at domestic violence shelters for several years, and it still surprises me how many women returned to men who treated them horribly and endangered their lives. Abusive relationships follow a cycle of tension buildup, followed by the abusive event (be it physical or otherwise), followed by an apology by the abuser, and then a honeymoon period where everything is OK. The honeymoon is the most insidious part of the abuse IMO b/c it convinces the victim that everything will be OK. The honeymoon, coupled with the low self esteem brought about by the abuse, makes it hard to leave.
I have a good friend who spent 5 years on and off with a guy who abused her. It baffled all her friends, b/c she was successful, smart, and an excellent athlete/outdoorswoman. But she stuck with this guy who treated her like sh*t b/c she "saw the good in him." (I always had Luke Skywalker flashbacks when she said that.)
Bottom line, she will need a lot of confidence to overcome her feelings for this guy and ditch him. I'll pray that she has the courage to do what's right for her.