This is a very well thought out take, MGB, but I think there is more to it. For instance:
1. She has been making a habit of being gone for long periods of time...sometimes for more than 24 hours.
2. Whenever he has wanted sex, she denies him.
3. The few times she has let him fuck her, she just lays there...really taking no part...except to let him cum inside of her. And her moans and such sounded fake to me.
These things have been going on long before the current events which, as I see it, started with that letter he wrote to her. I think she really doesn't like him enough to want to have sex with him.
These points of mine don't take away from your scenario. In fact, I think they add substance. If your scenario is correct, then her refusing to sleep in the bed with him could be her way of punishing him for making her sell sex.
One other point...the sex she had with that guy last night shows that their apartment will put them at a great disadvantage if they are trying to sell her body.
If your scenario is correct, then I feel very sorry for them. It would really be nice if someone who understands their language could report on their conversations.