In all otome Isekai manga, every 'protagonist' or 'rival girl' always try their luck in meddling in between a prince & his established fiancee, whether they meant it or not. Every fiancees have the right to put the meddlers in their place tbh but the princes always sided with the meddlers, no matter how two-faced & lacking social manners they actually are. This is what I learned from the 'villainess' side of the story, who sometimes are the actual victim of scheming bad girls. This time the cute interloper is also a bad one. Cunning & she knows how to use her cuteness as a weapon.
I'm surprised to think that I now agree with a harem type manga, if only for this MC alone. He can collect all the beautiful victim-girls if he wants, if he can save them from humiliation/sabotage arc lol. I approve of him because he's actually good to the girl (& hopefully to that idiot prince's fiancee next). If he's here than I hope he'll turn the tide against this unfair world. Even I (as a woman) dislikes this world's matriarchal but extremely sexist setting.