I Saved The Cursed Duke is a Manga/Manhwa/Manhua in english language, Fantasy series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Asteria who lives protecting the grave of the gods.
One day, a man who is on the verge of dying suddenly appears in front of her, disturbing her peaceful life. This man is none other than Duke Erhardt, the most handsome and youngest governor of the empire. Asteria saves the dying duke using her magical powers, but her magical powers can only be maintained if they are together.

At Erhardt’s request, she came to the outside world and became the fake duchess.
Will Asteria, who is slowly adjusting to her new life, be able to achieve love and solve the curse?!