Yup, I'll offer you a crack opinion. If by that you mean an opinion from someone who is cracked !
It is amazing, isn't it, how well someone like that can become more themselves and more pleasant when given more space (even if only by circumstances)?
This should not lead you to the conclusion that you are better apart than together, though.
In fact, I think it fits right in with my theory that he is expecting that a "good" relationship will be "perfect."
Here is the way I envision it: When you are together, there is minor friction between the two of you, because you live in the real world (as opposed to the "dating" world before you were living together - where you both covered up all your faults and showed only your best face, if you followed conventional dating practice). The little bit of friction makes him feel that the relationship is not perfect, planting in him the doubt that it might not be the right match. This makes him uneasy, more irritable, and further friction gets a disproportionate response from him, to which you react with surprise and anger (well, he is being unreasonable!), and from there it escalates.
Does that ring true?
Honestly, in a way, I think H needs to GAL! Not that he doesn't have things that matter to him, but I think he needs to have a strong enough sense of who he is that an argument between the two of you doesn't shatter his world. Of course, you cannot bring him to that conclusion. Heck, I'm having trouble bringing myself to that conclusion! It's a lot to change.
I'm really rooting for your marriage (praying, too). But if you did bail, I really couldn't blame you. I get the sense that he is really lucky to have you, and he just needs to wake up and see that.
Just a funny thought, for you to take or leave: Next time you two disagree, and he seems to be getting irritated, stop, kiss him ON THE NOSE, give him a huge grin , and tell him, "You're cute," (or some other such mild endearment) and see how he responds ! You might just derail him and open his ears long enough to tell him that your disagreement doesn't have to negate the feelings you have for each other. It may surprise you. Or, at least, it might be funny to hear how it pans out .
Think about it...if you met a potential mate who was nothing but a bundle of needs, would YOU be attracted to them?
! 
, and tell him, "You're cute," (or some other such mild endearment) and see how he responds 
! You might just derail him and open his ears long enough to tell him that your disagreement doesn't have to negate the feelings you have for each other. It may surprise you. Or, at least, it might be funny to hear how it pans out 
.
