Yeah they have a high about changing their circumstances. It's like a wolf in a trap biting off their own leg to get free. He's convinced his unhappiness will end with the move - he doesn't realize that it will just move with him, but he won't be able to blame you for it any more.
This is not about you.
Btw why can't he buy his own car? Get him to take his name off the tenancy as soon as you can; you can always add it back later if he makes a miraculous turnaround, but if you delay getting it done, he might refuse to do it later just to spite you. Strike now while he's happy about leaving (or pretending to be).
