I have to tell you, I'm very opinionated on this topic, but I want to know what everyone else thinks, too. I read a lot, mostly in the genres I write. Contemporary romance and YA (mostly spec. fic, though I like contemporary, too). I read because I want to keep up on what's popular in the genres I write. I read because it inspires me. And also, I read because I enjoy it.
Because of this, and because I don't have as much time to read as I like, I'm fairly particular about what I like to read.
If I'm reading a contemporary romance, I expect a happy ending. If I'm reading women's fiction or literary, I try not to expect a certain outcome because I know those genres don't always have happy endings.
But what about YA? See, most of the stories I read in this genre have a happy ending. And by this I mean the conflict is resolved, and (because most YAs have romances in them) the characters end up together.
Also, a lot of YA stories I read are part of a series. So, you're invested in a plot and characters for three or more books, I figure the reader deserves a happy ending. I figure the reader deserves a resolved conflict and characters that are in love (if the story had a romance).
I recently read a series despite hearing mixed things about the third book. I read Book 1, loved it, read Book 2, liked it, and then stopped before Book 3. I worried something was going to go wrong in Book 3. So worried, in fact, I read spoilers for the book so I could find out. And, upon reading those spoilers, decided not to read the book.
If I root for characters only for them to not fall/or stay in love, I don't want to read about it. If the character is going to die or not accomplish what they'd set out to do, I don't want to read it.
Basically, if this happens, especially at the end of a series, I feel betrayed. As a reader, I feel like the writer has betrayed me.
So, what do you think? Specifically in YA novels, do you think stories or series should have happy endings? Do you feel betrayed when you think there's going to be a happy ending and there isn't?