How is This Hot Duke Just a Background Character?!

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 chub