A brief description of the manhwa The Duchess With An Empty Soul:
I died a miserable death the day I learned the truth: my fiancé had a secret lover, and it was my own cousin.
The next morning, after my twentieth birthday, a miracle happened. From that moment on, I decided not to believe in love anymore.
Duke Agentin, will you marry me?”
This offer was nothing more than a marriage of convenience and without love.