I read an excerpt of a book once where the main character dies in the end. And not for a cause to save someone or anything like that.
She just dies.
I'm pretty sure I won't be reading that book. It just seems so sad... and hopeless... and pointless... The thing is, if I want pointless, I will just read the news everyday. I'm not going to choose it in my literature.
Reading is an escape for me. Not that I want to read just happy or funny books (frankly, I hate "funny" books), but I want to leave this world for a moment, with all it's depression and dysfunction, and go somewhere new where things usually end well.
True story... if my wife feels like there's not going to be a good ending to a book, she sometimes reads the end of it. If she doesn't like it, she just stops reading the book or skims it to get the high points of the plot. It doesn't make sense to me. I think she'd say that life is too short to waste on a book with a crappy ending. (I kind of see her point.)
My OCD won't let me do that, though. I once slogged through a book that I HATED because I just had to finish it. I mean, I hated the characters and the plot was so bad, but I still had to finish it. It took me months. (I finished LES MISERABLES UNABRIDGED quicker than this book.) I would complain and my wife would yell at me to just stop reading it. But I couldn't! It became purely bathroom reading material. You wouldn't find me reading it on the couch or in bed or anywhere else except for... the bathroom.
Therefore, because of my frustratingly amazing sense of perseverance (according to my wife), I have to be very careful of what books I read. And I can't go spending my time reading about how a character slowly dies, or how a husband leaves his wife, or a woman spends her time traveling the world after a messy divorce.
Now my mission is not to offend. This is merely my preference. I want a book to take me away to a place that I can't go everyday. It is one of the reasons why I prefer fantasy or science fiction.
I was discussing this with my wife, and she asked me how I could like all the classics, if I didn't want to read about hopeless plotlines (because I do like Charles Dickens and Thomas Hardy and Dostoevsky).
It's a good question.
I think the answer to that is that it's historical. It still takes me out of the modern day's mundanity. I can visit another time and place. I'm far removed from the current. So maybe in 60 or 70 years I'll be able to read today's depressing stuff.
All that to say... I guess I have rules about what I like to read (and write). And, I'd venture to say that we all do, and that's okay.