Melt Flirt Cookies summary:

Yeomin, a difficult person to communicate with, moves in next door and meets Hanbyeok, who is fed up with Yeomin for not greeting him back. That same night, Hanbyeok hears moaning coming from Yeomin's place, leaving him unable to sleep. He wonders if Yeomin is with another guy, though he's not bothered by that. The next morning, sleep-deprived Hanbyeok finds kiss marks all over Yeomin’s neck...