I'm glad he has come round, OP.
He sounds very similar to my EX, whose first reaction to any change was usually either a tantrum and outright refusal, or he was pitched into the depths of darkest despair, no matter how reasonable or necessary the change was.
In most cases I'd have to wait until he'd thought it through, or the rationale of the issue suddenly became clear to him, only in his case he would then think it was his idea so of course it was wonderful! The process could take anything from half an hour to several months.
What I ended up having to do, if it's any help to you, was whenever something cropped up that I knew would make him blow his top, I wouldn't tell him until I'd worked out the best way to 'sell' it to him, put a bit of positive spin on everything for him.
This meant I could never just say "Guess what?" or "XXX has happened" and then talk it through, as he'd sit with his head in his hands for days, it would be all my fault, and he'd point-blank refuse to see any bright side or show acceptance of the situation.. And withhold affection.
Of course this is very wearing, and is just one of many reasons why he is my EX. He refused to talk to anyone though, or would agree and make the appointment, then cancel it as just the very idea of talking to someone had apparently 'cured' him. Till the next time.
I hope your DH talks to someone and gets some help to see why his behaviour is unreasonable.
