Lost soul

My man has had a lot of family lose and heartache in his life but even so he is usually very strong and positive in life. Lately i noticed he looks sad and lost so i asked him what was wrong. He says he feels totally detached from everything. He says because he feels like this he knows he is a crap bf and feels guilty. I asked him if he would rather i stayed away for a while as he has enough to try and sort out in his head without me causing him more stress. I love him so much and it would break my heart to not be with him but all i want is for him to be happy and ok so i would stay away if it helped him. He says he has so much going on in his head he doesn't know what he wants. He is a good decent honest man so i know he is not just leading me on. I want to help him but he says only he can do that. Should i leave him to sort his head out or should i stay with him but step back a bit and give him space. I don't want to make his life harder but i also don't want to walk away from him when he is in trouble. How do i help him.