Herbalist for the Warlock

I must marry the strongest dark mage by contract, but I ended up in the house of a warlock who loves candy. He terrifies the servants, and his Darkness lulls me to sleep at night. At the gates of his castle lies an ancient cemetery, while in his study are living flowers in a fragile vase. My fiancé is the one whose birth date is not even recorded in the Book of Life, while I am a nobody, an ordinary person. My family has sworn a blood oath to this marriage, and I cannot refuse. But will I want another life once I learn what secrets lie in the territory of the abandoned greenhouse and what is hidden beneath the soulless façade of my fiancé, the most powerful being in this world?