I love the story and the actors, I just don't love how it ended. It is realistic, but for my perspective the boy is valid for questioning what will happen if he havent met the girl. It's more of his true emotion after what happened to his life, we all have that moments in life, where we start to questioned everything.
The girls emotion is valid tho however it could be much better if she understands the boy who sacrificed a lot for her.
Anyway 4/5 for me still one of the heartbreaking movies of all time. Ive watched the korean and chinese version i would say i like the chinese version more.