Seo-hyun is an ordinary housewife in her late thirties with a ten year-old son and a successful architect husband. For Seo-hyun, life is a series of banal routines, but she is well provided with upper class comforts. Her sheltered life is suddenly threatened with the appearance of U-in, her much younger sister's attractive new fiance. U-in approaches Seo-hyun and attraction evolves into a passionate affair. Seo-hyun is aware that falling for the younger man will destroy her and her family, but she cannot help herself and the new feelings that are stirring within...

An Affair (Hangul: 정사; RR: Jeongsa) is a 1998 South Korean film. The quiet film about a woman who falls in love with her sister's fiance was the seventh-highest grossing Korean film of 1998 and won the Best Asian Film award at the 1999 Newport Beach International Film Festival.