As someone who is the “third” in a scenario with my dear friends (I’m sexting and video chatting my best female friend who is partnered to her male soulmate, I’m also in a primary relationship with my partner who is long distance) I can say that I personally would have felt very anxious and upset being ignored or discarded. Fortunately that didn’t happen to me. But you’re right to worry about the other woman because she might have been like me, a demisexual, or she might have been just after some quick casual sexy validation and nothing more, but it needs to be communicated. Poly is so complex.