One of the problems may be that you are too attentive. He has to want to get out and when he has a lot of communication in the home he is less inclined to find it elsewhere. I know you are acting out of concern but you should also consider that he is participating in this isolative behavior. You may want to consider a therapist separate and apart from his condition. He could be suffering from a situational depression. This is brought on by circumstances. It has the same symptoms but can be treated very effectively. One of the symptoms is isolative behavior. He is keeping himself walled off from the world. This can be addressed in therapy. There is even online therapy now where he can get an appointment and participate by webcam or IM. You can Google that at etherapy or ecounseling. Don't move from helping him to enabling him. Consider this option.
Please press accept; this is the only way I am compensating