aw Jess, sorry he can't seem to give you the answers you need. Maybe one day that will come, in the meantime, if you can reconcile yourself to not having the answers it may be easier on you. (I had to do that with an ex... just accept things, and I did get the closure I needed years later when he called me out of the blue to apologize.. so random)
I'm guessing he doesn't really understand or know whats going on inside his own head. Because if he knew why he was feeling this way then he's an even bigger jackass for not sharing with you.
You deserve better and this limbo is not good for you. It sounds like its time to move on.
I'm sad for you though, it must still be hard even though he's making the decision an easy one (if that makes sense).
I'm surprised he has the ability to feel discomfort about what he's doing! Shocked!