Sob stories are often a red flag. Most people get themselves into bad situations because they are attracted to the wrong people. I'm assuming stories of abusive relationships.
Not to offend other women who have been in physically abusive relationships, but there's something they are attracted to in that kind of man. A nice guy isn't going to fill those shoes unless that woman has done some psychological renovation on herself and learned a lesson from it. Old habits die hard, and I would avoid anyone just coming out of a dysfunctional relationship.
The thing is, sometimes women will "try on a nice guy for size" after leaving an aggressive man, just as sort of a breather. However, as soon as she starts longing for that which attracted her to the jerk to begin with, she's off to the races again.
It's kind of an addiction really, and I don't know if it's excitement and drama, the negative attention or what, but many of those women will return to jerks over and over again, often leaving a trail of "nice guys" in her wake.