At Swim, Two Boys by Jamie O'Neill is the first novel I've read, I think, where the romantic story at the center is about two boys. It takes place in 1915-1916 in Ireland, a time period where you'd think they would be faced with a lot of negativity about their choices. They do, but that's not really at the center of the story at all. Also woven in is the Easter Rising, which both characters play a role in.
This is a really well written, sad and interesting book. Not necessarily something I would have chosen on my own, but I'm glad I read it.