It sounds to me as if you need to set some personal boundaries. I agree with the others, I really don't see any urgency or diligence on his part to work on the marriage.
If it is unacceptable to have sex one night and have him sleep in a separate room the other then let him know you have decided that will not happen again. If you feel okay about it and can accept things how they are then accept them and stop wondering and trying to mind read.
IMO when he moved back home nothing was really established as far as boundaries, joint goals and individual goals.
Why are you unsure how to communicate your boundaries to him? Do you feel it will cause a conflict?
