53 Letters for My Lover question

Can anyone please recommend a book like 53 letters for my lover. I want read a deep - love story which is mean full. Not just love story but a affair with cheating involved buts as with Shayda the heroine of 53 letters for my lover . The book should have valid reasoning behind and it should be a true deep mean full love story. I have also read and loved the education of Sebastian and the education of Caroline by Jane Harvey - berrick.

Thanks in advance.

Sonia x