Young-mi is having a hard time because of her boyfriend Tae-sung who always tries to sleep with her when they meet. One day, Tae-sung sleeps with a woman who approaches him and keeps it a secret from Young-mi. When they are together, Young-mi happens to see a text message from 'this woman' to Tae-sung. She gets her revenge and sleeps with Tae-sung's best friend.
The first two lovemaking of the boyfriend's girlfriend and his best friend (the bespectacled guy) seems to just be the best friend's fantasies. But their third lovemaking at the end part of the movie seems to be real as the boyfriend walks in on them.