The Key (1997)

Ikuko is a mature, reserved Kyoto woman married for many years to a respectable, now-middle-aged man. The only problem in their relationship has been that her husband is dissatisfied with her lack of passion during lovemaking. All this changes after they meet the young Mr. Kimura. After the three spend the evening drinking together and Kimura has gone home, Ikuko's husband discovers that his wife, in her alcohol-induced haze, has become far more passionate than she ever was before. The one drawback, however, is that her ardor is clearly fueled by Kimura, and not by him. Though he decides that his wife's new- found passion is worth this unusual price, the long-term consequences may be more than he bargained for.