Engraved Pleasure

Robert (the main character) is the prince of the Kingdom of Corinth. He had promised Arieno (the heroine), the only daughter of a farmer in the territory, that she would enroll in a military academy in two years. However, immediately after making that promise, Arieno disappears.Two years later, when Robert was about to head to the military academy, Arieno, who had become his servant, was waiting for him. Why did Arieno suddenly go missing, and what happened during the two blank years? Robert comes to know about this question through assignments at the military academy.