Bellxa

FL has white hair/blue(violet?) eyes, ML has black hair/red eyes. I think her name is Iris and her red haired brother name is orchid(?)(flower names). Her family are swordmaster(power)/has aura but she doesn't have it but is strong without it. I believe she is living her second life where she becomes the duchess by marrying the ML to save/help his life. She constantly cleans up her sisters mess and takes care of everything. As she leaves her family, she asks them not come looking for her when they need her to take of something/anything.

Can't remember more than that... thanks!