How is This Hot Duke Just a Background Character?!

Synopsis

I was reborn... as a background character in a romance game?! And my fiancé is a hot duke?! Reincarnated as 'Leticia', a background character in a game, I found out that my twin sister, who has a horrible personality, pawned her fiancé, Lionel, off on me. When I first met Lionel, he was just as chubby as I'd heard... But I soon realized he was a diamond in the rough and decided to make him shine! But that's when I discovered that my newly hot fiancé is acting like he's head over heels for me...! (Source: Pocket Comics)