Guys, if a King marries a Princess she can't be a Queen unless she is crowned Queen of...Coldplayland. It isn't an automatic change of ranking, she has to be crowned after the wedding.
Also, they're not a couple yet (I mean, in the song), so, she is still a Princess Of China.
(A very old one, there aren't princesses on China for a very very long time, but I'm digressing...)