Which is the Most Famous Love Story Book?

I’ve been thinking a lot about iconic love stories lately and wanted to ask everyone here: which do you consider the most famous love story book? Classics like Pride and Prejudice and Romeo and Juliet immediately come to mind, but I’m curious about modern takes too. Personally, I recently read a second chance love story book that really moved me it showed how love can endure despite past mistakes. It made me wonder if these kinds of stories resonate more today than traditional ones. What’s your favorite love story book, and why does it stand out for you?