The Fox makes adjustments to the terms
Chu Yun bit the inside of his cheek so hard he tasted blood. His uncle kept looking at them from behind the desk as if he had already won.
A few weeks into their marriage, Chu Yun might have accepted the proposal with glee, even after acknowledging he was being used as a pawn -- after all, his loyalty was to Xin. To his people. But things weren't that simple now, something like this would directly harm the common people of Zui, impact their livelihoods.
Even if Xiao Zai reduced taxes after he ascended to make up for the difference, it wouldn't be enough. It was the kind of thing that would stain his reign forever -- his first act as a King being the subjugation of his own kingdom in a one-sided agreement that didn't benefit his nation in any way.
It made him seem greedy for the throne -- capable of anything.
And while Chu Yun wanted to promote eventual trade agreements between Xin and Zui he wanted them to benefit both parties equally.