I don't think it was her cumming, she just lost her virginity, so she is still super sensitive, and she put her full weight on her vagina and it Jolted her. - at least that's what I'm assuming
Man, getting beaten up when you first meet must be quite the experience.
Still, it's always refreshing to have a chubby person be quite the decent sort.
A slender body with low fat, or a stonking great pair of tits? Such...A dilemma...