I personally kinda read it as his friend wasn't anywhere near as experienced as was assumed, and she wanted more than he was ok with. Or maybe you're right. Its ambiguous intentionally I'd assume.
I ran across this a couple years ago and just reread it today. I love how the narrator is about as confused by the girls as we are, and basically completely ignores what they say and focuses on progressing the night.
For instance, the second girl talks about seeing insect-eyed and winged people in Rio, and he just responds "uh, do you want to dance?". It definitely makes me realize that I've witnessed conversations at similar parties where one person(usually the girl in a girl/boy pair) could basically say anything without changing the flow of the conversation.
