I find a lot of these doomer characters adopt an "if it will end eventually, I might as well enjoy it" only to be constantly anxious about that vague end.
It's the fight between wanting to give in and be happy, but too insecure to think it's something they can keep/deserve. Almost like they view themselves as a placeholder till their partner finds someone "better"
But how can he enjoy it when he's always like "it's gonna end anyway" and literally anxious all the time
Well he's traumatised
If mc thinks he has to give up on ml at some point why would he agree to date