Are boys afraid of girls when they tell the boys that they like them?

Ignore those idiots who think they know what they're talking about.
If you're talking about when some boys avoid a girl who says she likes him, It's more complicated then that.
He could just be trying to think it over, Or maybe he does like you and is just shy. Or, He could not like you and be hoping you drop it because he doesn't have the balls to tell you himself.
There is also the event where he likes someone else already.
So no, Not "Afraid" so much as "Shy" generally.