Sis read the mood, the emperor does not give a flying fuck about you.
Sure she's not terrible at scheming, but she's horrible at reading people. 1) she fell for the bait even while knowing her sister isn't that stupid, who just drops evidence of a love affair on a rivals lap. 2) she forgot to appeal to the guy, he shat on you for wearing red yesterday. 3) When they are laughing together you assault your maid and blame her, you killed the mood and focused the attention on to yourself.