Well... it is her power, sure it seems that the tactic was thought by her mind, but her power forced her to say it... like we all have that one very inhumane idea to achieve a thing, but we don´t say it because... well, it is inhumane, but with her, if the king wills it, she will do everything, same thing with the marriage... she does not want to do it, but can't go against the king.posioning water supplies? damn girl, you're evil.
On the other hand... this MC is already in the capacity of just fly over the castle and just scare everyone with sheer power... but nothing happens?, well the marriage is already a thing, so I hope the meeting is near