Most Helpful Guy
What he's doing, he's doing for the both of you, speaking from experience, depression episodes make you feel like a burden to those around you. Also even if you don't ask much of him the little obligations he has to you feel much worse when the episode kicks in.
Sad truth is, there is no cure to it, you won't be able to just chipper him up. What you can do is be there, if not as a gf then as a close friend. Despite how much he's pushing, you need to pull harder and remind him why you're pulling, because he'll make every excuse in the book to escape the idea that there's still something positive in his life.
I won't bull shit you it'll be incredibly stressful for you, however.
Most Helpful Girl
I was in this exact same situation all though now we're back to dating, it's still a bit rocky, but only time will tell, depression can take over someones lives, I think the main reason he can't do the relationship currently because he knows he needs to focus on himself, and with you there he can't because he will be constantly worrying if he's pleasing you and its too much to handle at once. Ofcourse I was heart broken when this happened, but I was always there for him, and he saw that, as it became easier to love me and be with me that I didn't put any expectations on our relationship. You can't help him, he needs to help himself, keep in mind if you guys get back together your relationship will not go back to the way it is, it can only get better or worse, it's up to you if you want to support him during this vulnerable stage, I know its hard to see them close up and isolate themselves but there's nothing really you can do. Just give it time be patient and hope for the best, its hard to be happy with your relationship when you're not happy in general.