I'm curious is this pattern of Request-rejection-sulk made worse because it is to do with Sex or would people give the same replies over any request? Genuine question.
It's a good question rpitchfo because it gets right to the point.
You have to look at why people sulk. It is to convey, in a passive aggressive manner, that they are feeling upset, annoyed, angry, hurt or whatever else emotion it is they are feeling. It is to make the other person feel under pressure to change their mind, to feel guilty or to do things differently next time.
In short, it is controlling behaviour because it does not give the other person any opportunity to explain their reasoning, their own feelings or talk reasonably and constructively.
It is a very deliberate and ploy and the whole purpose is to manipulate or emotionally blackmail the audience. That is why no-one sulks without an audience.
Now, apply that to this particular situation and you see why that behaviour is so damaging to the relationship.
The advice is always to ignore sulkers because it's the only thing that works. However, in this case it allows the sulker to make life miserable for the OP, so she is still being punished for...what?
That is why I strongly recommend she leaves the house completely. Not in ltb way but in order to protect herself from more emotional harm. After all, she has done nothing wrong and does not deserve such contempt and lack of respect.