An Affair: Kind Daughters-in-law 2(2018)

Original title: 정사 : 착한 며느리들 2

Do-hee is alone in the house with her father-in-law as her husband is away on a work trip. One day, she sees him get bullied by his friends. Since then, she keeps thinking about his friend Yong-jin who looks strong and manly. Tired of being lonely, she seduces him. Yong-jin's body heats up for the first time in a long time and he goes to Do-hee's house every chance he gets to have a good time.