Well it sounds like you know what you're doing in the realm of communication. I don't know what else to say other than flat out asking "why are we not having sex?" or maybe even present the idea of couple's counseling. He could very well be dealing with depression and not realize it or what it's doing to you. And it may just take an outsider's perspective (a T) giving their professional advice or maybe even trying out some anti-depressants for the time being to see how they affect his mood.

Depression doesn't necessarily have to be caused by any certain event but moving, being unemployed and having some crappy jobs can really put a strain on a person. And if that put him in a funk he might just not know how to pull himself out of it. In that case I think some non-threatening couple's therapy could be very good for you two. The time to go see a T is BEFORE things progress to the point of resentment, pain etc... But, if you choose this option, I would make it very clear that you are not doing this because you are thinking of leaving or any of that but that you really do just want your relationship to be stronger.

Personally, I think all couple's should see a T at least every now and then just to clear the air in a safe environment and reassess their situation together. Might give you guys a new view on the relationship and create a new spark.