The main character is actually the psycho. Hare was just his illusion, and he fell in love with his illusion. He was actually in a mental hospital the entire time and was dreaming. He woke up ten years later and realize that Hare was never real. His brother (who looks exactly like Hare) told him that it isn't real, but he still believes otherwise. The ending was him walking into the ocean to be forever with Hare.
Psycho (Young Dream) Webtoon