So... The translation is appreciated, first off, and also withholding the tragedy tag at first.
I understand why so many are upset with the way the story went, and the word you're looking for is poignant. It does not deserve low ratings in my opinion as it's really quite beautiful, if heart-breakingly so. The author did a wonderful job of evoking strong emotions and really linking an invested reader to the characters, and what they felt: love followed by shock, sadness, disappointment. So many being upset demonstrates, in itself, that it's good writing; it should make you feel what's being portrayed.
No, it wasn't the fluff many of us expected, but for me it was definitely excellent and rewarding. I guess I'm reminded of something a professor said about love stories, "Remember, Romeo and Juliet is a TRAGEDY"