Having only read the first 9 posts of this thread, I'm going to try & explain a few things to lonilover.
1. Girls have always had less problems experimenting with other girls that men have had with other men (aka, girls are often bisexual, even though they may have a slight preference for men, while many men are either homosexual or heterosexual).
2. Many of the girls working in porn but also a lot of they girls with profile pages on ... (enter the site name on the dots) have boyfriends.
3. Many girls consider having sex with boys when they have a boyfriend cheating
4. Many boys who are dating these girls consider it cheating if their girlfriends have sex with another guy
5. Many of these boys don't mind if their girlfriends have sexual intercourse with other girls (some of these boys seem to think they'll be able to join the girls)
6. Many of these girls don't mind having sexual intercourse with other girls when they get paid for it, when they can get away with it without having too many arguments at night or when they want to experiment
The end result is that you'll see a lot of girls in porn, but also on profile sites who only do girls (besides their boyfriend, but they usually don't mention that...). There are also boys who pretend to be girls...