In past decades, pornography has been aimed primarily at the male consumer because the sexual desires of women have been repressed, denied or otherwise unexplored in society. Traditionally, women have found their outlet in romantic novels. Maybe there are fundamental differences between the sexes that affect how we look at porn, but society has surely formed our tastes and appetites. Whatever the reasons, the sexes are clearly divided on this issue. Not only do women and men differ in the quantity of porn they consume, they don't agree entirely on the type of porn that turns them on.
Women are also enamored with the action supplied by movies.
Maybe what is left to the imagination can be equally arousing for women. Women are much more likely than men to see porn as a tool in their relationships. So men like to watch porn in privacy, to fantasize alone.