One thing to consider is that therapy can help with grief like this. If his doctors haven't suggested it, then maybe you might. It's not fundamentally different from losing a loved one, losing a house, losing a job, ... Grieving is the way we adjust to any significant loss. Probably the thing that helps the most is to have support from friends and loved ones. He needs to adjust to the change in his body and his ability to function (and may need help with doing things until he is able to recover and learn to compensate), as well as to know that the people who matter still accept him and are not going to reject him.

Yes, the loss affects his wife too and maybe other people, so the grief process would apply to others besides just himself.

<font color=orange>"Success is the ability to go from failure to failure without losing your enthusiasm. - Winston Churchill "</font color=orange>