I think you are just seeing too much into this
And the other demons probably call her that cuz he has probably already declared her his wife
I agree with you. Cuz even if she didn't reincarnated, originally maise was with the soldier boy and the demon king just appeared afterwards and then there was the beginning of the conflict but since maise is now a living girl from different dimension she just makes her own rules. Sooo i think the demon king fell in love on first sight with maise or something like that and then declared that she'll be his wife aka the queen. But idk we'll see....
Her highness the queen....bring her ''back'' ....I smell some plot twist
So she was originally with him then something happened that separated them and she forgot....
But she transmigrated into a novel, was he connected to the novel's original protagonist or our mc ....
Or am I seeing too much into this x)