Thank you all again. I am worried that he will come back a different person. He's already changed a lot since starting this job... All I really want is for him to just "give up" and move to be with me but he might resent me forever if he does. There just isn't a clear solution.
I do think he's starting to see the effect the stress is having on him and he's doing things like working more from home, which so far seems to be helping but it's only been a week or so.

We've always felt rock-solid in our relationship but I've always been aware of the countless other people who felt the same only to have it end after decades together. All your stories help make me aware this could always happen and not to be complacent. I do know if we need to spend this time apart we'll both have to do all we can to make it work. It's the hardest thing I've ever done though and I wish he'd just decide to move here so we can grow and change together.