On one sitting from ch.01 ~ ch.75

Absolutely love it! First of all, her dad is super cute and funny.

Now...the FL is smart and strong but not in exaggerated way. She has a good balance. The "flaws" she has is stuff like bad at socializing and trust issues. But she is not like other stories where the FL is thinking that everyone she meets is gonna backstabbed her. What I like the most is that her other life wasn't in the modern era. She was actually someone that can kill, so I found it refreshing when she was able to do the same to the assassin. No FL trembling in fear of how she had to kill someone or having trauma and not wanting to do that again. Same goes with the hunting(animals).

The pacing is fast, but made in the right way. There is no useless chapters or something she noticed, then remembers after she is already in trouble or to check on it after a 100 chapters have gone by.

But anyways... even before she told the Devine Beast about the novel, my theory was like this.
What she thinks is a Novel is actually the future, like she is doing in this timeline. I believe the ML in the "novel" was just having a contract marriage with the brown hair lady. She needed a sponsor to get her family in the right track, and he needs a fake fiancé. I believe he also did this, to protect our FL. But this made her go the crazy route, cuz she thought he didn't like her and that's why he was getting married to another. So she become entangle with the Empress and the Temple.
Th Devine Beast said, the Pope looks super young and energetic. I think the medicine they have made her drink since young is from the Temple, in order to transfer her Holy power to the Pope.
Btw, her novel version refuse to drink that medicine, so maybe she knew it was poison.