The Enigmatic Demon Duke's Desire

The next day I woke up, I am now the fiancé of the Duke of Dubois Castle, or known as Lemon.
“I am a demon who lives by desire and greed, you have yielded with the contract that you have exchanged with your life?”
“Then what do you want?”
“I want the whole of you Veta Le Blanchet, not just your blood, heart and soul, it is the whole of you.”
Theroux Claude, the third prince of the kingdom.
“Lady Le Blanchet, just how can you stand still this demon duke? If you ever get tired of him, you are always welcome to my palace.”
Another troublesome man, my childhood friend when I was at the academy, Durand Gagnon.
“I have attained this nickname not just because I follow all his Majesty’s order, but because I want to have a stronghold in the knight position so that I can support you my Lady, remember that my oath is only for you.”
Then, what is my cousin thinking that he would say such things?
“Sister, I have finally inherited the title of the Baron, please come back to our fief, and I will make sure to bring back the glory of our family!”
As I try to relinquish the past, the more troublesome it becomes. Is clinging to the tiny bit of my life a wrong choice? And why is the temple spying on me?
“Lady Le Blanchet is the only descendant of the family, you shouldn’t involve yourself farther with the Demon Duke.”

“It’s done my Lady, as long as it is you, I can give everything, even if I destroy this Kingdom.”

Hold on, just what on earth this demon wants from me?