I think in the long run it's mostly an idea of the fact that we're hooked on stories of prince charming before we reach our sexual maturity mixed with the fact that girls mature faster than boys mixed with the fact that the idea of the sexuality of girls is taboo because it's desireable to men so it's often repressed so girls get the idea that they can't be sexual unless they're a woman, and even then sex will be had in an objectifying manner which involves having a perfect body and being on display, but none of that will matter because a real man can make you feel like a woman.
Re: serious business
I think in the long run it's mostly an idea of the fact that we're hooked on stories of prince charming before we reach our sexual maturity mixed with the fact that girls mature faster than boys mixed with the fact that the idea of the sexuality of girls is taboo because it's desireable to men so it's often repressed so girls get the idea that they can't be sexual unless they're a woman, and even then sex will be had in an objectifying manner which involves having a perfect body and being on display, but none of that will matter because a real man can make you feel like a woman.