Valid Love.

Jang Hee Tae met his future wife, Kim Il Ri when he worked as a temporary biology teacher at an all girls high school. Il Ri was a student there. Now, Hee Tae works as a fishery researcher and spends his days in a typical marriage. One day, he learns that his wife is having an affair with a carpenter, Kim Joon. He becomes angry for the first time, but decides to keep his family and wife.