My Sister’s Keeper was literally the saddest book I had to read in high school, and one of the only decent ones. You’d expect any book about a cancer patient and lawsuits to be sad, but… anyway, it’s a sad book, and I expect some of my imaginary readers also had to read it. If you haven’t, I recommend it, despite (and because of) it’s inherent sadness.
Allow me to say sad again, just for the record. Sad.