Mythical or Historical love story like Song of Achilles

Suggest me a book which has a love story that builds up slowly and intensely with a mythical or historical background. I read Song Of Achilles last year and I constantly think about it.

In fact I loved 11/22/63 and I really enjoyed the part which focuses on the relationship between the two characters.

I want a deeper love story which may or may-not have a happy ending but is matured.

Thanks

Edit- Fixed a typo