The power Pretty holds here is pretty minor. He's helping her get into conferences and mentoring her. He "controlled where she was staying" in the sense that he made the reservation for their AirBnB. He's not confiscating her passport, she isn't destitute. She could've gotten another hotel, hostel, AirBnB. To be clear, I am not saying "She didn't get another room and so deserves to be raped" but I am saying that his "power" in this regard is pretty minor - just because someone is paying for your room that shouldn't make it impossible for you to say "No" to them.
A big part of why it is morally and legally wrong to have sex with children is that children aren't mature enough to make decisions about sex. Children cannot consent. You seem to be suggesting that a similar standard applies to this adult woman - she can't know if she consented to a sexual encounter or not. To me, that implies you are suggesting it should be illegal to have sex with this woman - after all, she apparently can't tell if she consented or not.