Bleak books about feeling alone in the world

Depression, ennui, existential anxiety, isolation, heartbreak, etc. No happy endings, please. Looking to feel understood, not uplifted.

I’ve already read No Longer Human, A Little Life, Norwegian Wood, Notes From Underground, Stoner, White Nights, The Bell Jar, I Who Have Never Known Men, The Stranger, Crime and Punishment, and Madonna in a Fur Coat.