The Wellesley saying goes, "BU to bed, Harvard to wed, MIT to pull the sled."
Is it more disturbing if a man were to successfully deceive a woman into believing that he goes to BU (thus achieving "bed" on false pretenses) or believing that he goes to Harvard (and achieving "wed" on false pretenses).
Are the rules of society to control sex or to control marriage? I suspect the latter, because marriage and children is how culture gets passed down from generation to generation.
Granted, the distinction matters only in rare situations, e.g., a culture with a lot of casual sex (an activity psychologically separate from courtship, if such a thing is even possible), or perhaps activities akin to such casual sex.