ASAI Sora

The falsely accused daughter wants to believe - The Viscountess, whose engagement was broken off because her silver hair was considered unlucky, seems to be enjoying her second life, being doted upon by an assassin nobleman... Iris has been betrayed by her fiancé and best friend and has been falsely accused. She is in the depths of despair when an assassin is sent to kill her. However, the assassin does not kill Iris, but offers her a contract as a “fake wife."

It's basically Cinderella with alchemy