What novel do you vote Worst Ending?
Since this is essentially the spoiler thread to end all spoiler threads, please start your answer by clearly stating the name of the book, so that anyone who doesn't want to know the ending can skip over your answer.
Amsterdam, by Ian McEwan. (No relation, heh.)
I won't even bother recounting what the ending actually is. As dreadful as it was predictable. I read it ages ago, and the thing I remember most is throwing the book across the room in disgust when I was done with it. (Which, come to think of it, I did with Atonement and On Chesil Beach, as well.)
I don't even know why I keep reading his books. Their endings are all crap, and he routinely submits his female characters to sexual assault. (No wonder he wins so many awards.) Wevs.