What does it mean if a guy doesn't call?

no, men are famous for their inability to remember the simplest things no matter how important or how many times you remind them (reminding them is called 'nagging') it is more likely it has completley slipped his mind, and if you complain he will not understand what he did wrong. Just wait a little longer, he is bound to remember in the end. If on the other hand he didnt call because he is no longer interested, then you'll know because he wont call you at all. Assume he's not interested.