I say listen to the girl.
I add, when you are in moment with him, he is open like a vessel. Tell him “u suck” 
No’ don’t!!!
Tell him you got to make peace with your scars.
His 98% problem is gone by having you in his life as a person who knows his pains.
Plus way you describe his personality, this thing wont do him any serious damage(every thing else being stable around him).
Its nothing more then an old sports injury which bothers you every once in a while 
He is lucky to have you(as a friends/listener)