An Affair (1998) on Netflix

A woman in her late thirties, married to an architect in Seoul, with one brattish son and a life in dire need of a service, is asked by her sister, who lives in America, to help her fiancé find an apartment. He is 11 years younger, tall, serious and attractive. She begins to look forward to their journeys. He does more. He recognizes something that she has long forgotten - her beauty and sensuality. Their affair follows a recognizable route from sexual excitement to anguish and guilt.