Yes, as someone pointed out, there was no "Sweet". This was a very sad (and sadly common) story. As KD lovers, even if there is no happy ending, or no ending at all, we at least get to dream about neverending loves. That's how we tend to forget that there is no such thing... The film left me very distraught, it was hard to sleep after that.
Still. It was good. It's true that the nurse was never in love with her patient, but it was obvious to me from the beginning. People use other people to move on, that's just how it is. Also, people drift apart when all they see of each other is routine and exhaustion. On the contrary, people get closer when they share their time and interests. No happy ending, no great love story, just bare, real life. We can't hold this against the movie. Just. If you're in a long distance relationship, avoid watching, it WILL bring you down.
The ending was as satisfying as could be. There was no "loop", and the story wasn't "re-written". Pay attention, the story doesn't change. It's just a smart, brillant, and very satisfactory plot twist that sort of relieves, a bit, the sourness.