Stephano saw Desmond and Leonor go under the walkway and out of the ballroom to cool themselves off. He could justify their departure considering they did as they were told and took part in the first dance–even going so far as to participate in the second one and only leaving when the room was satisfied.
In the King's opinion, however, Quinn didn't have an excuse for leaving already. He wasn't required to greet anyone but he could have at least stuck around and waited for him considering he was supposed to be his mage.
Seeing Cian gone as well made Stephano's head feel hot. Would it be like before? Would he find the two of them with one another as they commiserate over-hating the palace?
Stephano bit his lip and had to hold himself back from making himself bleed.
Quinn knew that he hated the palace, too, so why wouldn't the mage vent to him instead? They had years more friendship than he and that knight.