I recently read a blog post by Tim Sunderland about happy endings, or at least hopeful endings. He'd written what he thought was the perfect story. Although he knew it was the perfect story he wrote an alternate ending that wasn't as dark as the original. He read the story to the writing group that he is a part of and they loved the story. They didn't really like the ending, which was bleak. He read them the alternate ending and they loved it.
There is little doubt in my mind that Tim wrote a compelling drama, and I'm equally sure that it's a great story no matter which ending he decides to use. I disagree with Tim and the group that fueled the opinion that all stories must leave a ray of hope. I think I'd enjoy the darker version. Those are the kind of stories I write. Those are the kind of stories I enjoy reading and I am not alone.
When you read a book you escape to another world. The people who read stories where the endings are dark; those people want to know that someone has it as bad or worse than they do. People love conflict and conflict drives these kind of stories. The drug addicted, gambling addict, non child support paying father doesn't have to turn it around. The story could still be good.
People who read horror are rarely looking for a happy ending. It's not just horror fans that expect darker endings. The story that Tim wrote is about a couple trying to save their marriage while dealing with a drug addicted teenager. That does not have to end on the bright side, because 90% of the time it doesn't. The reader can only expect that situation to go one way...bad!