Here's what I see: I think you are afraid of love. This sounds very ethereal but I'm serious. I went through something very similar to you when I broke up with an old boyfriend. It was very hurtful in the end and it took about 2-3 years before I dated again. When I got into my new relationship I felt similarly to what you described, but I stayed with him, I did not realize it at the time but I kept sabotaging true intimacy and closeness. My experience of this was feeling "unfulfilled", not realizing that I was causing this. Recently he said he had enough, we almost broke up. I tried to picture my life without him and began to cry, I went through some deep stuff finally realizing that I really love him. I realized that because I was so hurt from past relationships I had prevented love. I had been preventing him from fully loving me and me for him. When I told my boyfriend that I saw this and I was ready to be open he said now we can begin having a real relationship. Once I had this ultimate shift in love and consciousness we were able to start a new relationship. Everything is different now.
I think healing from a long-term relationship is hard but the best way in my opinion is to move through it with someone who really loves you. This woman sounds dedicated and involved. I would sit down and sort out my emotions, find out if you love her. Explore your feelings and the depths of love/feelings together. Be healthy follow your heart; give her a chance, a real chance this time to have a real connection with you.
Open your heart and your mind your body will follow. (Meaning once you do this it all falls into place)