Why Do So Many Guys Think That if a Woman is Being Nice, She Must Want Him?

Via Reddit:

This is the source of a LOT of heartbreaks and hard rejections (eventually leading guys to TRP). A girl is nice/respectful to a guy or wants to be his friend and the guy immediately takes this to mean she’s interested. So after some time, he makes his move and is shattered when he’s turned down. Often he claims that the girl lead him on when there was never any talk of romance/sex.

Why does this happen? Does kindness=desire in our minds? Were men taught that women can’t purely want friendship? Is it something deeper?

First of all, keep in mind that when you start out as a guy, no one gives you a manual explaining how to tell when women are interested in you, yet you are the one who is always expected to make the first move.