When I lost my Mum last year it took a good six months before I really felt human again. My brain was overwhelmed with processing my recent experiences for a full month. I dreamed about it every night. It was literally like a computer working at max just to keep doing the basics. I didn't have any extra space for anything that could wait, until my brain was freed up again.
Just be there for him and let him work it out. Hugs are always good. And having someone take care of the day-to-day crap that you can't be bothered with is wonderful (like food, shopping, bills, phone calls...).
Tell him to sleep more, as this helps with the processing. Well it helped me anyway. He'll get there with your love.