Wabbitz
Actually one of Indonesian current hottest romance novel (because adapted to movie) didn't end with a good ending. I don't think readers would read/BUY the last novels. It tells about 'Senior High School' love. It was common those love would end. In the end both married their own partner. Some movie watchers had decided to stop watching the next series of the movie and novel from the spoiler. Nobody wanted their 'dream' to be crushed.
However, I believe nobody would read that author's book with sadist ending. So VERY Bad idea for a novelist who wanted to grow readers.
You don't want your novel to become a Good Written Novel which could add 'discussion' for some novel professors.
You want a BEST seller novel which could net money for author and entertainment for readers. (Nobody remember novel award winner ten years ago. However, I believe everyone have heard the best selling Novel series of all time, Harry Potter or the second best, Lord of the Rings series.)
That is a good way to lose fans. By becoming a SADIST author.
Nobody like real life store. Novel is an escape. Why read novel when you can 'learn' the pain in real life.