What does it mean when a guy does not text me back?

Is it true that guys would rather keep you waiting than cancel on you? and then send you a very late text to say he won't be able to make it! Or is this a 'nice' way of blowing you off without having to say something like I don't want to see you tonight actually. I am just having casual sex with this guy, I knew he really wanted to see me and he knew I really wanted to. And now nothing, he asks me when he can make it up to me and I ask him when he is free? I mean how hard can it be to reply, I can't do anything until...i mean really!? what goes on in the minds of you people! And before you ask I am starting to like him that's why I am going all clingy right now. Any help will be much appreciated. Thanks