I think you've got it right; she doesn't want to get involved and hurt again.
My question would be...why does this behavior intrigue you? The on-again, off-again seems to hook you.
So I would ask myself "why?" Perhaps you have just as much fear, so you get involved with others who are similarly afflicted. If you are developing a pattern of these kind of relationships, perhaps you protest too much regarding THEIR intimacy issues.
She's made it clear she won't get close to anyone, so don't expect a sudden change; life with her will always keep you on edge. But maybe you seek that, too. Otherwise you would seek out someone who can freely give you love. Good luck.