Thumbs up for The Last Unicorn by Peter S. Beagle. Fantasy.
This is a book that raises a quandary. It is one of the most beautifully written books I've ever read. Each line is like poetry and there are a dozen passages I want to copy out to savor again and again. But it is also one of the most heartbreaking books I've ever read. There are signs, early on (perhaps the title is one), but the mood builds throughout in understated but absolute ways until the second half is suffused with sadness; even when it is funny, which it frequently is. So I would say, if you like fantasy, read it, but pick your moment, and have something light planned for afterward.
"Well, if they hadn't [abandoned him], he wouldn't have grown up to be a prince. Haven't you ever been in a fairy tale before?" The magician's voice was kind and drunken, and his eyes were bright as his new money. "The hero had to make a prophecy come true, and the villain is the one who has to stop him - though in another kind of story, it's more often the other way around. And a hero has to be in trouble from the moment of his birth, or he's not a real hero. It's a great relief to find out about Prince Lír. I've been waiting for this tale to turn up a leading man."