anyone know the novel where Fem Lead has amnesia and she psychologically regresses to her young age around when her mother committed suicide and now the Male Lead (he's the bodyguard knight sorta thing) is in charge of her work till she gets her memory back. The only reason why she got amnesia was cuz if a poison in her drink. She was described as a "true villainess" since she only had relationships with people for business purposes, even around her family. She has red hair and was pretty cold to people. Engaged to the crown prince. Crown prince doesn't like her and tries to kill her with poison but that fails. The knight/bodyguard is taking care of her work until she recovers her memories. Realizes that the Fem Lead has been preparing him for the moment when she cannot take care of household duties. Fem Lead has trauma from watching her mother hanging herself.
The description is pretty different from what you gave but it’s the closest thing I can think of from the description of the story and the description of the novel I remembered, it’s most likely not it but I’m gonna leave the title here anyways “Don’t Shame The Villainess”