July Rhapsody (2002)

High school teacher Lam Yiu-Kwok is in the midst of a midlife crisis. His wife, Man-Ching, has been unfaithful; his friends are reaping the rewards of successful business careers while he earns a comparatively meager salary at an unglamorous job; and one of his young students, Choy-Lam, has fallen for him. When Man-Ching leaves for a month to help her former lover, a jealous Yiu-Kwok is tempted to retaliate by pursuing an affair with Choy-Lam.