I'm not sure about the term 'midlife' crisis, because I'm not so sure that the actual timing of it is the issue, but I'm convinced that there is something identifiable, something with a recognizable pattern, happening to people who are in the midlife crisis category on this board.
Whatever is going on their heads is not any fun. My H said at one point that 'everyday is torment' and I think in a lot of ways it still is for him. There don't need to be two of you trying to make sense of it - if you can, try not to analyze what he says. Something I've heard often lately is to not believe most of what they say and only about half of what they do.
If you're not going to believe it, you might as well not think about it, right?
Practice thought stopping - find something to shift to when you notice yourself trying to figure him out. I use the red hand on the 'don't walk' sign. If I find myself stuck in a certain thought pattern that is causing me distress, I picture the hand in my mind and tell myself to stop, then force myself to think about something else, something positive. The more I do it, the easier it gets and I feel much better than I did when my days were spent dwelling on my H and I miserable I was.