Tipper, they usually need someone they can 'help' or rescue, feel better than, and be miserable with. I suspect that your h is a 'glass half empty' sort of guy at the best of times
For so many MLCers it is about feeling unsuccessful relative to what they feel they should have done and/or those around them. Your h cannot live up to you - this is not your fault or your problem. .
We cannot fix them, sad though this is. We go on thinking we can, or that we were at fault. We should work on ourselves, but that is in order to live our lives. If it is MLC we didn't cause it and could not have stopped it, nor can we fix it.