Negative Boyfriend

My boyfriend is so negative about anything that goes wrong in his life. He shuts down, is moody, and doesn't want to do anything. I've dealt with anxiety and depression and have come so far in my life that I'm afraid he's going to start affecting me. We've been together almost 2 years and love being with each other. He refuses to go to therapy and just continues to act this way. Anyone dealt with this and what was the outcome?