Yea this girl really is off her rocker. Roughly grabbing a princess, talking down to her, threatening her, you'd think she was trying to ruin herself. Not only is the princess of clearly higher rank, her engagement was determined by the kings, so by attacking their relationship (however recent and impersonal it may be) she's actually going against the king's authority and risking insulting a foreign nation. So nice to see the princess just brush her off like nothing, and in fact she's already being quite indulgent, she could have given this girl way more trouble if she wanted.