I've Been Proposed to By a Villain

Whisked away into the novel The Forbidden Fruit of Isotta, and the body of Regina Blois, our female protagonist has the advantage of knowing how her story unfolds—which is that she is to be murdered by Duke Arsene Graroy! Her death moves the story forward and sets up her good friend and protagonist Isotta in a love triangle with the Emperor and the Duke when she tries to uncover the truth behind Regina's death. Not wanting to be murdered this time around, our new Regina keeps a low profile. She still manages to catch the eye of the Duke, but when he confronts her this time, it seems he's less interested in murdering her and more interested in... marrying her? (Source: Tappytoon)