Dase to Iwareta Reijou no Kareinaru Henshin

Clarabelle, who grew up in the countryside, skipped a grade to enter the academy in the royal capital in pursuit of her fiancé Alan, who is from the same hometown. But as soon as she enters the school, she witnesses Alan cheating on her! He dismissed her, saying "I have no love for a plain, unsophisticated woman like you."