yanno, thinking on it, though it's true he is Bahamut and a soldier of the Empire first and foremost, his place mainly on the field of battle keeping his men safe and leading them to victory, but he is also the Emperor's son, raised in a court of politicians and royalty and I have not a single doubt about the fact that he also knows very well how to handle the politics side of it too. He certainly seems to have the respect of the members of the chamber and if it hadn't been for Ultima fucking up his coup, I have no doubt he would have succeeded; at least, for the time being. Basically, tldr; he knows how to play the game. So if he were to be forced into a bethrotal, while he sure as fuck would be angry ( and he'd be open about it while in the privacy of his own tent, like we've seen him get pissed off at some of his father's commands and updates ), he'd not actually become openly defiant until he knows he's in the best possible position to do so━ and until that he is going to politic his way out of it in whatever way he can.