Why are guys so shy about talking to you?

Sometimes, if a guy is equally attracted to you and he shows all the signs that indicate this, yet makes none of the moves he may be too attracted to you to be able to speak to you. No lie.
Some guys are shy and more introverted than most guys are stereotypically thought of as being. People don't get it because girls are supposed to be the ones who are like this when it comes to dating and flirting. It's more acceptable in high school for a girl to be shy and reserved than for a guy to be this way.
Guys are supposed to be "more assertive and the ones who make all the moves and say all the lines."
But, no guys aren't all the same. Many do and many don't. Just depends on the guy and his personality.
Also, he may have experienced rejection in the past when he did try to approach a girl he liked. So, he now is just trying to do whatever he can to never experience that again, even if that involves nothing at all or being to nervous to even talk to you.