Looks like Yuri's got some conspiracy brewing. Her flaunting of informal influence is very remniscent of the imperial consorts who brought their countries to ruin. Now that she's been seen entering the dens of crime and poverty for a purpose, I'd suspect she's up to something nasty. Those places are full of men who use violence to achieve their ends, and they are always searching safety and wealth. What if the gifts that Yuri insists on getting are being funneled to these men in return for their service? And is she not using her influence to flaunt her ability to give the forces of corruption the ability to act with impunity? That would put Yuri in the driving seat where she can exert influence through organized crime. Her weakness, however, is that she can only exert influence on the men she has captivated with her charm. She uses her words to infect men with her dreams, an affliction that enfeebles them by removing their mental connection to the reality in which they live. If this affliction were cured, there would be no use for her in noble society - she is a thing that defies their rules, insults them, and diverts their resources to folly. Once she loses power, she will be cast off.
And that brings us to the ballroom scene. Yuri's insults to Iris backfired on her. By insisting that Iris had no rights to attend, she slighted the Queen Dowager and her partner's family. The first prince's faction strengthened while hers weakened, which will harm her long term position as the second prince's consort. She made unreasonable demands that made Iris look strong, and made other major blunders. Iris was completely victorious, and Yuri's dependence on the second prince grew even more. Iris, who was already cast as Yuri's enemy, appeared to be triumphantly victorious on her return to noble society, diminishing Yuri's influence even more. The straw that broke the camel's back, was that Yuri has lost the support of Iris' brother. He had been thoroughly cured by his sister, and saw Yuri as the useless thing that she actually was. Iris appears to be stealing Yuri's important allies, growing in strength while undermining her. Can Yuri, an emotional person, handle that? No.
Yuri is going to try and arrange Iris' assassination. Too bad Iris has got the best guards, is suspicious of her, and has a feeling that something is wrong.