Most of the people who buy erotic pictures and videos are men. Most of the people who buy erotic novels are women. Men are very visual, while women seem to have the need to incorporate more emotion into their stories, if not romance, then at least, the psychology of what the people involved are thinking and feeling. A female friend said to me the other day "I don't get why any woman would want to read that stuff. I can HAVE sex if I want to. I don't need to read about it." Which is good for her, of course, but not all women are so lucky. What I said to her was that while I don't know her sexual fantasies, many, if not most people have sexual fantasies which they have no hope of ever bringing to life. Whether it's an orgy, or having sex with a room full of bikers, or being a slave to a handsome Arab or Spanish man, or woman, most people lead rather mundane lives. They have active fantasies, but they know that, due to their own fears, their families, the pressures of society and it's taboos, they will never really get to carry them out. If you're a relatively conservative woman married to the same sort of guy, leading very vanilla lives, you're just not going to be involved in a wild sexual incident where you, for example, become a temporary stripper and perform lap dances and have sex with strangers. Nor would you want to. Not really. Any more than you want to be raped. But the fantasy is not the reality, and a lot of women like to indulge these fantasies vicariously through the female characters in erotic novels.
The book I'm finishing now features a woman who works in a high pressure job in a bank, and just chucks it all, trades in her car for a Harley Davidson, and rides away, winding up in a biker bar as a semi-unwilling stripper having sex with people right out in the open in the bar. My previous book was of a woman who gets a contract to catalog and sort the books in a wealthy man's new castle, and of course, winds up in a BDSM relationship with him. Before that, was a woman just about to turn 30, realizing she'd done nothing exciting in her life. She goes to Rio, and winds up in a BDSM relationship with a handsome Spanish millionaire. Before that was a young woman who wound up in a torrid BDSM affair with her aunt's new husband. And before that was a young archeology student who gets lost in Africa, and enslaved by an Ethiopian tribe. These are all fantasies which women would probably not want to experience in in reality. But in the safer realm of written fiction, anything goes.