See, the king got invited as a matter of course to all manner of events going on in his kingdom. Tourneys, feasts, balls, festivals, and yes, even weddings. It was a courtesy and an expectation among the high nobility to invite the king. Even if he would very much like to go to some of these events, he had to politely decline the vast majority of them as a matter of practicality, saving what valuable time he had to indulge in such affairs for the most politically expedient or important reasons. By all rights, the marriage of Duchess Stormcrown's daughter, who had an… interesting reputation, to some lower standing clan would not be one such event.