Oooh. How interesting would it be if he knocked her up, she loses her regal status as a prince and therefore ability to be come king... then the BODYGUARD becomes the king, and the Princess becomes the queen? The hottest and least violent coup ever pulled off!
The thing is, we don't know if she was the crown prince, or just an excess prince. Just as we don't know how she ended up a she (unless it's somewhere else and I missed it?) For all we know the King might be really happy about this.
I wonder what brought about the need to transport the Prince is such a manner? Personally, I'm hoping this all started as an elaborate prank that got out of hand.