The Hole (1997)

Newlywed, Su-jin, believes that nothing will interfere with her happiness or come between herself and her husband, Dong-woo. That is, until she meets her mother-in-law. Dong-woo is devoted to his mother and now that they are all living together, it isn't long before Su-jin notices something unnatural about the amount of affection between the two. When confronted, Dong-woo promises his new wife that she will be his priority. However, he must spend a lot of time away from home because of his job granting the mother-in-law sufficient time to plot how to eliminate her rival.