My Engagement With The Prince Was Cancelled So I Will Stop Pretending To Be a Fool is a Manga/Manhwa/Manhua in english language, HISTORICAL 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

It is mid-spring in the country of Brior. Olivia, a duchess, pretends to be a fool under the order of her fiancé, the crown prince, Alan, and suddenly, he tells her that their engagement has been annulled. Olivia was stunned, but she was even more confused when the second prince, Cyrus, suddenly appeared in front of a large audience and asked her to marry him. This is a romantic love story of a genius daughter who is inexperienced in love and a prince who wants to make his long-time love come true begins!