When: The equivalent of 15th-ish century England
Googled: non-royal spouse of king/queen, non-noble spouse of king/queen, spouse of king/queen, how would a non-royal spouse of a king/queen be addressed, how would a non-noble spouse of a king/queen be addressed, how would a commoner spouse of a king/queen be addressed, gay spouse of king/queen, gay lover of king/queen, gay royal marriage (yep, all of it's related)
Okay, here's the situation. MC, through a long process that's just a little too complicated to get into, finds himself in service to the king. After moving up the ranks in the King's army, he is named heir to the throne (the king has no kids, no spouse). King dies, MC becomes the new King. Beau of King finds a way (still long and complicated to explain) to get to his man. After more long processes, they decide to get married. How would the subjects of the kingdom address Beau? I can dig out the details of the wedding, there's a post about it on here.