Smarie, maybe you are just done with him?
I have read about how a damaged relationship, hurt, lack of trust, anger , resentment, etc. affects peoples' heads, esp. in the sex department.
Maybe all of your work to detach--know it's hard--is kicking in, and this is just another signal that you are ready to move on.
I think SmallButMighty's post hits it right on the head.