Hyeon Dae and Min Joo thought one of them getting married would end the sex-partner relationship. However, they can't hold in their desires and Hyeon Dae destroys himself with sex, while Min Joo can't give up what she can't have. At the same time, they have a complicated and ugly relationship with past characters.

Young and beautiful woman, Shin-hye, she is a good housewife with all of her focus on her husband and housekeeping. However, she has a concern these days. She and her husband are drifting apart from each other, while her husband has been refusing sex with her and treating her like a ghost. As her unhappiness with her husband is growing bigger, she attends her high school alumni meeting, where she encounters her first love, Seong-jin. Shin-hye is drawn to Seong-jin, who is a cool handsome grown-up man now. She slowly steps into the forbidden realm, as to say ‘affair’ in spite of herself.