It's very possible that he has shut down because of everything he has been through with his divorce and the heartbreak from that and his injuries. It's important that he talk to a counselor and get therapy to help him through everything he has had to endure. His wife left him and then tried to make him think it was his fault and in his mind he blamed himself even when he found out she was cheating and still blamed himself. He can not understand that it was his wife's indiscretions and not his. he finds it hard to trust now and often shuts down when conflict arises so not to be left because of his unreasonable behavior label his wife put over his head. It is going to take some time for him to get over the hurt he has felt from that. Right now it seems as though he feels that everything that happens to him he deserves and that isn't always true and he just had a string of bad luck.
The emotional roller coaster after a relationship breakup left him feeling like his heart was been broken into tiny pieces. He may feeling grief, betrayal, and even some anger. It's likely that he just want some relief from the broken heartedness but maybe don't know how to get to a happier place. He should try to first let go of the past and second take charge of the recovery process. The letting go will take a long time, pain and suffering before healing, the process may seem to be so slow. The second method, taking control of your feelings and realizing it was his fault, will allow him to healing faster, leaving space to find healthier and more fulfilling love than ever before. He needs some guidance on the steps for a fast and productive emotional healing and a counselor can help him to do that if he is willing to consider that and is ready to heal.
He may think because he has to get counseling that it is definitely his fault but just because a person seeks therapy does not always mean that there is something wrong with them it just means that they are not able to handle things on their own and need help taking control of their life back. I would tell you to suggest some type of counseling or support groups for him, he cannot do it on his own he has tried that and it is not helping.