Why might women fear rejection and disapproval much more than men do?

I'm not, and I'm a woman. But, I think the biggest reason some women do, is because society has set rules for us. We're supposed to look a certain way, weigh a certain amount, talk the right way, have the right hair color, have the right job, and a whole list of "must haves" that society has set. Many women are tired of having to be a certain type before a guy would want her, and that's not the way it should be, but it is. Men don't have to worry about those standards as much, and they are not berated like women are for these things. If men would grow some and respect and treat women (especially good ones) with respect, then there wouldn't be such a fear of rejection, would there?????