I know right, there are going to be people who thinks she is stupid to be so forgiving towards Maylene after the torment she has out on Nullitas. However, I also find this to be sort of refreshing. It's so very true that holding hatred for too long wouldn't be good so she most likely forgave but won't ever forget, that doesn't mean she can't give Maylene, who clearly has became a much better person, a second chance and to work alongside her for their House. They are the only sisters and children left of their Household along with the former countess who took a huge step back to let Nullitas lead the House. Not only is she a Countess but also a Duke's wife, so she is a mighty strong woman who uses her power to punish and correct the laws to give women a better chance at life.
My girl is so forgiving, i could never. Kudos to her though