Book with a relationship like: “Given a different time and place, we would have been great together.” (But don’t get together)

I’m looking for books where there’s a ‘what could have been’ relationship between people- like if circumstances were different, they acknowledge they would have been a good couple. Kind of wistful.

Can be any gender, and can be YA or adult

I hope this makes sense and isn’t too specific 😅
Thanks!