What are some movies that fit the following the description?

Try 'the fault in our stars'. Problem is of course, this is a plot twist that you kind of don't see coming until it happens. I'm sorry that I ruined that for you, but you asked.

EDIT: You might want to further specify whether you want this to be contemporary or not. I think there might be some American civil war or World War I movies out there that have a situation like that (starstruck lovers, boy goes fight in the war, girl/wife stays at home, boyfriend dies). But given the age mentioned, I reckon it needs to be a high school sort of relationship?

I forgot to mention that I've already seen "My Girl", "Keith", and "The Fault in our Stars", and I was just wondering if there were any others. Sorry for not mentioning this earlier.