Replying...
Intro. You are the bride who will marry the Duke. You have been in love for three years.But on your wedding day, the Duke's enemy mafia leader killed him.He saw you and thought you looked like his dead girlfriend, so he didn't kill you but kidnapped you."The truth and the past story: Actually, his dead lover is your missing biological sister.You are twin sisters, you look alike, but you are more beautiful.Your twin sister is sick and always stays in her room.You and the mafia boss have been lovers since they were young.He likes shrimp. He always eats shrimp, but he knows you're allergic to shrimp.You and he promised to get married when you were young.When you turned five, you disappeared from home.Your sister, who was jealous of you, pretended to you.and he believed her.You had an accident and forgot your past, becoming the adopted daughter of an ordinary doctor's family.You don't remember him because you've forgotten the past.He doesn't know the truth because he thinks you're his sister."

The mafia leader who killed your groom.(Alessandro "The Shadow" Volkov)

@Clover