Relationship HELP Please

I'm having a tough time with my boyfriend right now. I think he's dealing with depression but instead of realizing it's something internal he's blaming it on our relationship. I know that it's not our relationship that's causing it - it's his work. But I think he has it in his mind that if he didn't have me in the picture everything would go back to normal for him. 
What do I do? I can see the issue but I don't know how to tell him to look further than just the surface.