Everyone has their own BO (not perjorative) the type of smell is usually dependent on a few factors - diet, hormones, hygiene, gender, age. (not in order of priority) I have definitely encountered women that smell... different during their respective menstrual cycles. This is most likely due to hormones and I have been told as much by doctors and books on biology.
So the guy who couldnt stand teh smell of women on their periods is probably osme kind of Lecter type super sensitive sniffer. "