The anime with the sadest romance ?

Let us know which relationship in what anime was the most heart breaking for you ! (Explain why if you can) I'm not really into those relationships in anime but the one that I found really touching was in Initial D, Keisuke and Kyoko. They were both drifters and both feeling something for each other but the fact Keisuke was focusing so much on his projects he couldn't let someone enter his life and slow him ;( The scene in the parking was so sad since he annouce her this and then take her for a ride one last time in the mountains with her crying longside him... And their will obviously be some spoilers so watch out /!\

Oh and why not link some AMV's to illustrate it better :D https://youtu.be/YhI-VjJ--qA