I like-hate how an illness can make a person bitter. The original,princess wss cold already and was turning her into a bad person but the breaking point and for a turn of never come back wss the bad attitude of the prince/fiance and the supposedly sweet and naive FL. This is why doing nothing and being naive can be horrible bad. They are ignorant and uninterested to see how their naiveness destroy people life.
I like jow the author shows this. That type of person could remain naive forever, learn how her naiveness could be used for evil, or change...but i would say the FL decided to be naive for a good time and learn to use to her favor without a desire to see how her wishes harm others.
Go, new soul. The villainous gave her blessing to start this new life however you want it xD. A brand new world