Will make a brilliant segment of the groom's speech someday 😅

"Have your cake and eat it" comes to mind. Unfortunately, I don't think this will leave his system, which is a shame because you're clearly doing all you can to understand what he wants/needs. You sound like you're handling this really well tbh - a lot better than most people. He thinks he's seeing greener grass when all he needs to do is tend to his own turf. I hope he eventually sees that before he throws away a good thing.

He sounds like a tool. Sorry you made so much effort just to be treated like that.

Try introducing him to the calendar on his phone, and insist on him adding an entry everytime you tell him something. Unfortunately, I used to be like him, but, this helped change that.

It definitely matters. Find someone at the same stage of life as you.