The Fan (1949)

Lord Windermere appears to all, including his young wife Margaret, as the perfect husband. But their happy marriage is placed at risk after Lord Windermere starts spending his afternoons with an adventuress who is working her way through London's high society, Mrs. Erlynne. Worse, Windermere gives her big sums of money. To crown it all, he asks his wife to invite the detestable woman to her own birthday party. Upset and outraged, the puritan Lady Windermere decides to leave her husband and goes to Lord Robert Darlington, who has been courting her for some time. Unfortunately she leaves her fan--the one Robert offered her for her birthday--in Robert's house.