If she was in a relationship for a long time then odds are you are not going to get anywhere. Women are led far to much by emotion and even if she is not as happy as she could be, or is getting treated like shit she will still probably stay by his side hoping things will work out. Better off...
Kids what do you say to the nice man walking down the street ? Are you my daddy ?
Heh I'm a single dad, and met a girl alot like the one you are talking about. Trust me, stop having sex with her and leave. You sound like the type of guy that once you have sex with a girl she can do...