Aside from all the social taboos on casual sex for females, I don't think there's anything wrong with a female to engage in it, especially if its with a particular guy on a regular or semi regular basis. Women want sex too. we are all adults. And there are many times where we aren't ready for relationships or don't want to get our feelings involved.
So. why is it that every time a girl agrees to one of these situations, guys think it gives them the right to be a total douchebag to the girl in this agreement? I have seen it happen over and over. its like, even if the girl is seeing other guys she makes sure to stay incognito and not shove it in the guys face, because god knows he would throw a fit (or in some cases i have seen, punch a guy.), and the girl obviously has enough respect for the guy to hide it.
But the guys just don't give a fuck. They will do whatever in front of the other girl, then when the girl gets upset act like the girl is out of line, then apologize, then do it all over again. Or if the girl realizes she is getting too attached and wants out, the guy will do whatever he can to keep her in that situation, and continue to fuck her over on a regular basis.
maybe this isn't all guys. but it's definitely the ones i have seen and interacted with lately.
maybe all the guys i know are just assholes. who knows.
it is tiring to watch and to be a part of.