Conundrum

It's considered "male" to be the one doing the penetrating, and "female" to be the one being penetrated. Every guy only has 1 dick, and every girl has three holes that can usually accommodate a dick. Technically, a man can only be male with one woman at a time, while a woman can be female to three guys at a time.

So why is it considered normal for a man to want more than one woman at a time, while it's considered improper and slutty for a woman to want more than one man at a time? And why do so many men have problems with the idea of sharing their woman?

I wonder if I'll ever understand humans...