I'm almost certain she was just trying to push his buttons and gaslight him into having his mind play tricks on him the same way she had to second guess if he was cheating on her.
Because of the convo that happened at dinner between the four, she knows now that Ethan feels some kind of way about Cameron fukking all of the chicks Ethan was into. So she has that little power to dangle over him - the idea that Cameron could win this dikk measuring contest by fukking his wife. I think she's playing with it to get under Ethan's skin, maybe into hoping that his jealousy could rile him into desiring her.
I don't think she actually wants to screw Cameron though.
We'll see in an hour or so.
Yea I think she still wants their marriage to be OK and just wants to feel desired by Ethan again and is trying to do so by making him jealous.