What book(s) have you read with a great, unexpected romance?

For me, it was the Winternight Trilogy by Katherine Arden. I went in for the Russian folklore and then was so unexpectedly emotionally invested in the romance subplot by the end.

I love it when books have a romantic subplot that does not overshadow the main plot, especially in a fantasy setting.

(Alternatively, do you dislike when books have an unexpected romance? What books did you feel were not as good because of the romance?)