That one tricked me at the beginning I thought it just another love triangle with betrayal and such then you start to feel the uneasy creepiness of not certain characters but all actually breliant layout of every detail and if you pay attention to camera angles like I did you might get the answer even before it's revealed.
I admit I tend to get frustrated with such endings but well it doesn't make it any less breathtaking and now I wish I could have read the novel to see how all that is written.
Highly recommends watching it and reading the book as well won't be less amusing