[@Ellion]
Lol and it's a woman so mistress over master.

Yea I can imagine it grinding on his soul every time he has to say it.
He spits the word out with an undertone of spite, the only dab of defiance he can add to his otherwise submissive obedience.

They both know it is not nessesery, but no matter how many times she makes him say it, he cannot rise above the pettiness of it and just accept it as an empty word.

No, it's a tormentitive reminder, a subtle jab to the guts, a selfish game.