The Villainess Who Stole the Paladin's First

I reincarnate into a villainess, Elenia, who eventually dies out of deep jealousy for the saint. If that weren't bad enough, I reincarnate into her body the day after she seduces the saint's most loyal paladin, Laurent, to spend a night with her. I insist that nothing has happened between us, but Laurent urges me to take responsibility for taking his virginity. Later, he negotiates with the emperor and asks for me. I, Elenia Arpine, am the sole thing he wants.

(Source: POCKET COMICS)

Note: First released in English, with the initial eligible release in Japanese followed by Korean, making it a manga by our standards.