The way you handled your H's sitch was exactly the right way to deal with a mopey 4. Mopey 4's don't want to bring other people down. They know that their way of looking at the world is sick and twisted. They wish there was some way NOT to look at the world that way, but that's the way the world looks to them (when in that mood) and to deny that (i.e. act cheerful when you don't feel cheerful) feels like existential dishonesty.
So providing a level mood yourself, keeping yourself busy, checking on him every now and then, but NOT jumping in the pit with him-- that's perfect. And I think you're very close to the next step (if not already there), which is to do this because it's best for you, and not as a resentful reaction to what you perceive as character weakness on his part. Very good job!
