Paramour 

A family misunderstanding leaves Merry and his mother to live on an island away from the city, and away from Merry’s father. Twenty years later, Merry’s mother falls sick, and she asks Su-Ho to help care for them. Believing Su-Ho is his half-brother, Merry can’t understand his aversion to touching. But there’s a family secret yet to be revealed, and Su-Ho is having a hard time keeping himself away from Merry... (Source: Lezhin, edited)