Because guys don't generally want to "take it slow" when it comes to sex. Women do, and for good reason. Once you start to have sex emotions start to settle and then attachments. So it is smart to take it slow and in that women are smarter than men, then again, I think men can fall in love quicker than women so... maybe waiting for sex isn't necessary for men. My own point of view. But I'm single asf so who am I to give dating advice. lol fml