If she's walked before and ends up wanting to walk again, chances are these are her issues that she doesn't want to address that you may or may not be exacerbating, and she doesn't believe in her heart that she can navigate back to "happy" with you.
As you probably know, the only way she's going to overcome that deeply held belief is for you to open the cage door and completely cut her free. If you engage in a relationship with her again it should only be under the conditions that:
1) She sees you as someone of extremely high value 2) She views a relationship with you as something much better than a life with someone else or a life alone 3) She's willing to work to win you
Without those three things, she's going to walk again down the line, because she really doesn't have the motivation to work with you to change anything, your relationship will keep seeking the same equilibrium it has had because of how your personalities and issues come together.
