One of the main criticisms of most horror writers is that the story is great right up to the ending. Stephen King often has this stigma attached to his works. People like his novels right up until the ending, which they usually say ends flat or unsatisfactorily. Horror movies usually get the same treatment; people love the build up, but not the resolution.
I think I know why. Horror stories, at their heart, don’t have satisfying endings. True horror stories, the stories of real life killers and tragedies, don’t end with heroes riding off into the sunset. Often they don’t end with the bad guys getting their just desserts. That’s just life, and it’s the nature of horror.
The horror writer is screwed in two ways. First is that if you go for the realistic ending, it feels wrong to people because people don’t want stories to end the way life really works out. Second, if you make the ending tie up all the loose ends, giving people what they claim they want, you get an ending that sounds forced.
It’s a narrow path to walk, wrapping things up just enough without tying it up so tight that it feels wrong. No matter how good of a writer, the ending will always trip you up.