Haha, we all need a cute Disy by our side, but ew, I'm so done already with Yuriel and the stupid King, wtf, I want her to get lost forever but I know we wouldn't have a story so *sighs* >XD
If the way it was drawn is really intentional, then I'm sure the emperor is left handed. Look at the way the tableware is put and the obvious when he wipe his mouth 😉
It was because he felt the princess was completely uninterested in him. It's not like he wanted to be wanted, of course, but the Princess literally waged war, destroyed his country, and got thousands of innocent lives killed, just to fuck him. Basically, to him it would have seemed like the Princess thought so lowly of his country and its people that she could just dispose of him after so little time, without hesitation, despite her actions taken to acquire him.
He's also probably wondering if he should just have become her fucktoy when she asked since she would have been 'disinterested' really quickly and there wouldn't have been a war.