Hakushaku Reijou wa Kenen no Naka no Elite Kishi to Kyousei-teki ni Tsugai ni Saserareru

When the Principality of Arita was conquered by the Skinia Empire, the children of the nobility were taken to be educated at the empire's academy. When they reach 18 years of age, they will be paired off in arranged marriages to ensure assimilation into the empire. And so the countess Tiana was paired with the elite knight Adele, who have never gotten along even as they grew up together. Their first night passed without romance, and Tiana thought that was enough to fulfill their duty. But Adele keeps coming to her again and again. For duty, or for something more!?