“Mothering Sunday” (R, 1 hour, 44 minutes, HBO Max) A gentle, involving romantic drama based on a Graham Swift novel that concerns a house maid in post-World War I England whose employers are away on Mother’s Day, giving her the rare chance to spend time with her secret lover, who’s engaged to the daughter of his parents’ friends. But unforeseen events will play havoc with her plans. With Odessa Young, Josh O’Connor, Glenda Jackson, Olivia Colman, Colin Firth; directed by Eva Husson.