Going only from what I've been told: it could be any or all of those, about trust or fear or pain. Emotions play a bigger part in sexual satisfaction than the movies would have you believe, and even moreso for women. It's not a stereotype to point out that most men are primarily turned on by visual stimuli, while for women emotional involvement is what's most important.

Being celibate for two years isn't necessarily enough. You may need to be with someone with whom you're solidly emotionally secure before you can enjoy yourself again. You'll have to have some serious conversation with your partner about this. You may also wish to look into professional counseling for a short time to understand what it is you want and need. (No one likes the idea of needing a counselor, I know, but I also know that sometimes it's the quickest and best road to emotional healing.)