Three In A Crowd (1989)

Lo Hin-chung is a contented veterinarian, while his mother is a domineering intellectual. He marries his childhood sweetheart, Fong Mong, who becomes an art director with the help of director Fong Kim-ting. Fong Mong's half-sister falls in love with Fong Kim-ting despite him being married, and their affair causes problems in her marriage with Hin-chung. Meanwhile, Hin-chung's brother tries to save his own failing marriage after cheating on his wife.