The difference between the sexes...
I don't profess to be an expert on the subject, but I've read a fair amount and done some informal polling of both guys and gals and the feeling seems to be that we're just wired differently. A woman needs to feel loved, to feel safe, to feel secure with her partner. She needs to know that he loves and respects her willingness to share herself in an intimate way.
A guy ... a guy just needs to be awake.
Am I wrong about this guys? No offense, of course. : )