All This, and Heaven Too (movie, 1940)

When lovely and virtuous governess Henriette Deluzy comes to educate the children of the debonair Duc de Praslin, a royal subject to King Louis-Philippe and the husband of the volatile and obsessive Duchesse de Praslin, she instantly incurs the wrath of her mistress, who is insanely jealous of anyone who comes near her estranged husband. Though she saves the duchess's little son from a near-death illness and warms herself to all the children, she is nevertheless dismissed by the vengeful duchess. Meanwhile, the attraction between the duke and Henriette continues to grow, eventually leading to tragedy.