During the weeks prior to my W dropping the bomb, she seemed to act withdrawn. I kind of knew something was not right, but, like a dope, I didn't confront it. I just figured that it was just another one of her mood swings and she would eventually get over it. Boy, was I wrong!
I think that your Hs quiet, introverted behavior is a sign of depression. My W had no idea that she was displaying depressed behavior. I brought it to her attention in a caring, non-confrontational manner and suggested that she mention it to her therapist. Eventually she started, and is still taking meds.
Part of the depression stems from your H being in withdrawal from his A. Unfortunately, this is going to take time and you really need to be patient about it. What you can do to speed along the process is not to bring it up in conversation. Let you H have this time to observe your new behavior and confirm in his head that he made the right decision to remain with you. Your H is mourning the loss of what he thought was true love, and at the same time he is uncertain that any of the DB changes that you made are for real.
If he reacts the way my W did, then he will begin to come around slowly. When he does, don't get too excited. Let him know that you are interested but let him know that it is ok for it to happen on his time frame.