(re: Kings Quest 7 – Valanice still Queen?) If you’re the King or the Prince, then of course you barge into a place (to assert your manhood and your position!) and announce “I’m King (or Prince) so-and-so of such-and-such a place!”
If you’re the Princess, you do pretty much the same thing, because you assert your eligibility to be married by some handsome Prince.
But if you’re the Queen, well the King has all the power 😉 and you’re already married, so how often do you announce yourself as “Queen so-and-so”? Maybe when you get older you announce yourself as the Queen, but when you’re younger or middle-aged, you say “Lady” because it’s more elegant? More “proper”?
I dunno, just throwing around some ideas.