I can't really explain her (can't read minds... though according to what you said she does want out from her other relationship), but what I can say is that I think you should just stay in the game. Now it's up to her who she wants to choose. Go out on dates other than walking down the trail (maybe coffee, a meal, a movie, golf, bowling, whatever) and see how it goes. Don't rush things though, you'd scare her.