I wish I could explain it. I think it has to do with the confidence that thugs project and the security the good girl feels. Or maybe it has to do with how these young ladies grow up.
Your right about one thing, it definately sends the wrong message to our young brothers.
The funny thing about it is, if the nice girl wants to separate from that thug, she might find herself trapped in a situation that she can't handle. It's an unfortunate yet classic turn of events.