In all honesty the king  wouldn't be able to leave without making a scene. It would have been impressive and only because people assumed she'd only be gone a moment that the princess was able to get away and because of the activity at dinner she could stay away unnoticed by most.<br/><br/>From my point of view you have a few options. You could utilize the fact that I assume one of the bloody ravens would have followed her given they are not restricted by social rules as your character would be and one is assigned to her and use them to irrupt and put and end to things or just stand guard over her whatever.<br/><br/>Your could over look her prolonged absents in the face of the busy and a touch hectic dinner service.<br/><br/>Or of course you could go for shock and aw breaking it up and causing a scandal.<br/><br/>Just as a note for all. Some one would know what was going on, at least one servant watched the princess join the swordsman in his private solar and tongue will wag.