Kawaisou na Kimi ga Ichiban Kawaii: Inukei Shuuchaku Danshi Haru-kun no Shitsuke Koubi

While exploring her masochism fetish by reading hardcore r18 manga, her neighbour Haru discovers her secret. “You've given me some wild fetishes, and now you're acting innocent. I can't tolerate that.” Her masochism drove him insane, and his obsessive love made her learn who he truly is. (Source: DLsite, translated)