As we are in a sentimental phase, here is a real tearjerker.
I chose this version because, even if you don't like the story, or the animation, you can listen to the Borodin 2nd String Quartet Nocturne played by the excellent Emerson String Quartet.
This is a real problem story to produce. Lovely story, but tragic ending. A number of versions I have seen have left the ending deliberately ambiguous. I have even known adults who have grown up not realising what the ending is.