I understand. I've been through the same thing. My last ex was understanding, and tried to work with me. A couple times, I was able to enjoy it a bit. But even the tiniest little thing could snap me back into dissociation. It's irritating, but I think it would be useful (for me, at least) to be in a relationship where I trust the person a lot; so far, I've been unsuccessful in that area. It did help for me to stay in the moment; are you familiar with grounding skills? Just focus on current feelings, current emotions. Maybe have your bf help talk you through it, to make sure you're not dissociating.