Find That Book

So I read this book when I was in 9th grade or something and I read it in French, but its most likely not a French novel from a French autor. I don't remember much, but its during World War 2 and there's this german soldier who falls in love with a girl that is most likely Jewish. He actually helps her and protects her, he calls her Fraülein, I don't remember her name but I think his was Hans or something. I think he helps her and a group of her friends or whatever escape/rebel/I dont remember exactly, or at least tries to, and he accidentally gets shot by a Jewish guy (in a tunnel ?) mistaking him for an enemy, and dies. The lady will later marry the guy who shot the soldier.
Its not much, since its been what 10 years now that Ive read this book, but hopefully someone can help !Thank you !