One of the most important rules of emotional intelligence (my version at least) is never to treat someone better than they treat you. This can be in 'micro level' interpersonal relationships or on the macro level - group to group relationships. Specifically, I'm talking about the relationship between men in general and women in general.
Most sexually attractive guys feel bad about using women for sex. We know women often want more than this, and society shames men relentlessly for this sort of behavior. If you feel bad about using women for sex, stop right now. I'll tell you why you should never feel bad for women in the dating game.
Dating, on a generalized level, is a transaction of sex for commitment. The prototypical female waits for a man to commit to her before having sex, and the prototypical male waits for a woman to be 'worthy' of commitment before he commits. The friend zone occurs when a man commits to a woman too soon, and the woman is free to use him for his commitment without giving anything in return. Women, and society, in general, have absolutely no empathy for such men - in fact, they are often mocked and abused by the very women who should, theoretically, be merciful to them.
A woman who is 'cruel' (I don't think it's cruel, personally) enough to put a man in the friend zone is essentially no different than a man who uses women for sex. Both parties fulfill their evolutionary programming at the expenses of someone who wants more. The only difference is that, while most men feel bad about using people like this, women do it gleefully with practically no guilt - in fact, they rationalize that they are doing the guy a favor. No matter how 'sweet' or 'innocent' a girl looks on the surface, almost every single one of them has played dozens of men in this way. She doesn't feel bad because of the female's naturally reduced empathy for males.
Teachers Note: It is the fact that women have reduced empathy for males that gives them greater power in the SMP... Also note, the men with the greatest empathy for women (mangina's male feminists, etc.) almost invariably lose while the men with the least (pimps, gigalos, etc) win. Those rare women who have an abnormally high empathy for males are the closest things to 'unicorns' and are the only ones suitable for LTRs - such heavy-handed tactics need not be used on such women.
When you come across this girl, and you want sex, but she wants a relationship, what will you do? You will play her just like she would have played you if the roles were reversed. And you won't feel bad about it. This message is intended for alpha males only; betas need not read or respond.