I also wonder whether this ambivalence will be a recurring pattern that’ll put a strain on our relationship

I'd have to guess yes.

It sounds like the 2 of you are incompatible. I can't imagine someone taking an entire year off as a 'gap' year between finishing university and getting a job. That's just... strange. But believe him when he is so clearly showing you who he is. His life, his choice. Your life, your choice. They just aren't on the same path.