Welcome to psyche central.

I believe relationships evolve in stages. The honeymoon stage is the easiest and funnest. Once that is over it starts taking work. Communication skills, overcoming fear of commitment, fear of abandonment, fear of intimacy and so on. For some people it is too big a hurdle. It takes two willing people to do the work and grow together. I would say you have to figure out if she is willing or not. If she is not there is nothing you can do.

I have been through that wringer before a few times. I got dumped and couldn't stop thinking about her and getting back together, couldn't eat, couldn't sleep. It triggered a lot of issues for me. Eventually it did get better and I did get over it but it was a lot of pain. I hope for you she decides she is willing but it is up to her.