妹に婚約者を取られたら見知らぬ公爵様に求婚されました (Associated Names)

Amalia, the eldest daughter of the Earl’s family, is cuckolded by her younger sister, for her fiancé. Even though she wants to break off the engagement, her parents won’t take her side because the fiancé claims that his affair was just a momentary lapse. At a party that she attends to distract herself, Amalia complains…