@MasterPannya
"
Next chapter is the Heroine conspiring with the neighboring country, starting a civil war and successfully massacring the Royal Family.
The End."
Honestly, even that twist wouldn't make up for how bland, generic, and forced the early narrative content was. Most people'd still be dropping a series before it reached that twist. That said, that kind of twist and shift-in-focus would definitely help redeem this uninspired, dubiously arranged mess.
Let me add the following continuation to your plot twist, as well:
Once the Heroine massacres the royal family, she apologizes to the villainess and attempts to repair their relationship. The Villainess, being treated with genuine warmth and affection for the first time, slowly develops feelings for the Heroine. The Heroine, no longer manipulated by family or the prince, also discovers that her happiness lies within her own decisions and in relationships with people who will actually treat her well, rather than in relationships done for social advantage.
Romance blossoms between the two, leading to a happy ending scene of them both snuggling up to one another on a window seat at the top floor of the royal castle, looking down upon the kingdom which had previously hurt them, and relishing the fact that they both are now in control of their lives and have someone who will properly support them. Second to last panel will be of the Heroine giving the Villainess's hand a squeeze. The final panel will be of the Villainess turning to face the Heroine, and both happily smiling at one another.