He doubled down on it when it wasn’t really acknowledged. After he said he wasn’t paying, she responded with an explanation for why her friend was coming. I mean she did say ok, but that might be agreement or just a way to move on the conversation. Like, “Ok, but what if I told you…”

It’s not clear if the new explanation was meant to change his mind, but the only change between that and the fake explanation before is his statement that he wasn’t paying under the first situation. So it may have been a negotiation tactic. Either way, if this was real she should explicitly agree that he isn’t expected to pay for her friend and he should obviously not be so crass about it.