Maybe it's the age difference? "Dangerous" guys aren't really the kind of men women want to settle down with. They're fun and exciting, but that wears off once the woman wants to get serious and they're still trying to have fun. It could mean she's not really ready to be in a serious relationship, but likes hanging around with you because you're a stable adult that she can lean on when she needs to. It could also mean that she might want to try out a serious relationship, but is kind of warning you that it might not work out because she's into a different "type" of guy that you are. So... she's either going to want to just be good friends or she's going to do what you said and date you for a few months and then break it off because you're not what she really wants.
I'm not sure that she can change if she's really looking for a dangerous kind of guy. You can try to make it work by doing something out of the ordinary once in a while. It doesn't have to be anything that's not true to who you are... maybe just something you've always wanted to try but were too afraid to do (if there's anything like that, lol). Hope that helps!
Me 34 H 37 M 12/97 H moved out 03/09 D 05/10 S 17 D 12 S 11