That is exactly what I was going to say. He just explained it in that one sentence.
angelica, Mrs. H is right on. Your H feels inferior to you right now and he can be superior to the ow because she is so beneath you in every way. He's the "better" half of that relationship and that feeds his depression. Good God, if you ever saw the ow my H was with...ridiculous. He's a good looking man, he could have done far better, but he affaired down, too.
Most of us really marry only once. First love endures, even unto our dying day. And we never really divorce.