Looking for a book with the vibe of State buoni se potete

Hi everybody!

I am looking for a book with the vibe of the ending of the movie.

Spoiler alert!

So in the film the loverboy doesn’t know that the lovergirl became a nun. As the loverboy is condemned to death, he asks the girl to put in a good word for him with his husband.

I like the bittersweet ideas of what ifs,”. And I like the unfulfilled love

Thanks in advance and please excuse my English if it is incorrect