This can't be the first time she's been fucked in the ass, but she is still learning to get used to it. Sounds like she started enjoying it for a while, but then it began to hurt too bad. It'll be longer next time, and every time afterwards.
to cjhotbaby :Its clear she is up for this video and whatever happens including anal fucking the only readon she is saying nono is that she is worried about what the guy will think of her afterwards