Ryuu no Kuni no Madousho

Just before her wedding, her fiancé eloped. Betrayed and humiliated when the incident was reported in the social newspapers, Erika, the daughter of a prestigious family, secretly worked at the Royal Library. One day, a plain-looking young man with glasses came looking for the "legendary grimoire." While helping him, Erika fainted the moment she touched the book he was looking for, and woke up in his house! He was none other than Mircea Antonescu, the legendary, stunningly beautiful wizard. However, Erika had been cursed with a "dragon transformation curse" related to the grimoire, and small horns began to grow on her head...

A draconic fantasy of love and curses between a cursed young lady and a legendary wizard!

(Source: Shueisha, translated)