Because they are girls, they believe they ought to engage in sexual behavior in order to please their boyfriends.
He goes on to explain the health risks of anal sex, how to modify the anal sex seen in porn, how to make sure your anal experience is a positive one and what should we be telling our children about anal intercourse.
Another perspective includes the idea that sexuality is individual morality; this encourages girls to make their own decisions, as long as their decision is to say no to sex before marriage.