I guess you could try going to him at least once when he is on the couch and see what type of reaction that it brings out in him. If it is good or bad, at least you know where you are at on this path.
I can see why he would have a hard time with adjusting to coming back. Maybe he has lots of feelings inside that he does not understand and since he does not understand himself, he is secluding himself.
You said that he was moody and had his ups and downs before. Tell me if I am wrong, but did he have problems with being able to communicate his feelings before the affair to you?
My H always told me that before I came along he had no idea that he could have any other emotions but a bit of happy and anger. My H has never been good at expressing himself either and when he does it is usually the 'wrong' way. He would leave for hours and not answer his phone. He would go out a get ripping drunk and when I would ask him what was going on, he would just say that he could not handle how he was feeling at the time.
Maybe your H is having difficulty with his own emotions and is pulling away from you by sleeping on the couch, thinking that if he distances himself from you then he won't hurt your feelings, you won't argue, and/or he will have room to think. In your mind this is wrong, in his mind it is right.
Try going to him on the physical level and when you are finished, let him know that you love him and that he may join you in the bed. Then head there yourself and get some sleep. Hopefully he will come to his senses and follow you.
Hang in there and keep posting. We are all here for you.
Me-31 Him-28 D1-9 D2-6 Married 5-06 Seperated 12-07 He filed 1-08 Reconciled 4-08 D dropped 7-08 Bomb dropped about H's activities outside the marriage 4-21-09 Filed for D 4-28-09 Trying to make a go of it 6-09