A book featuring a couple with a stable, healthy relationship that is never a source of drama

I’d like a book that includes two characters who are either together at the beginning of the story and still together at the end, or get together over the course of the book but their relationship is never a major plot point, just something that happens alongside the overall plot. In the ideal world, a sapphic couple but I’m honestly not picky. Just curious whether a book like this exists as I feel the romance in a book is generally used to generate drama. They can be side characters, not just the protagonist