Kon'yaku Haki Sareta Gakeppuchi Reijou wa, Teikoku no Koutei Denka to Musubareru

Exiled from high society by false accusations, the duchess Minerva is heartbroken after two broken engagements, and had given up hope for marriage. One day, while being publicly scorned and humiliated at a tea party, she meets Rufus, the second prince of the Empire, who is widely feared as "The Dark Prince." Rufus admired how Minerva acted resolutely without losing her composure, and proposed to her right there......?

(Source: Comic Gardo, translated)