I think one of the main reasons this is so common is because we're all led to believe that men are non-stop sex machines. Then, we hit the real world and learn how painfully innacurate that is.

Honestly, it makes me feel really bad for men, because they often have insecurities about not living up to this standard.

It goes to show how the same we all are... everyone has their stereotypes and insecurities that are challenging.