Kekkon Aite ga Komyu Sawa Hakushakuda Nante Kiitemasen!

Chloe Browell, the eldest daughter of a count, is not on good terms with her step-mother, nor with her fiancé, Emile Coltrane. Then, at a masquerade ball, Chloe witnesses her step-sister Beatrice kissing Emile. As she sits on a bench and tries not to cry, a mysterious man wearing a white mask hands Chloe a handkerchief and then walks away.... A few days later, Chloe is told that her engagement has been called off, as Emile has chosen Beatrice to wed instead. Chloe is told that her new fiancé is Friedrich Blysche, the infamous "Devil of Blysche"...?

(Source: Luna Bunko, translated)