Someone asks you if you heard what happen to one of your close friends. As you listen, you wonder, "How come I didn't know about this?" Think about how this lack of communication made you feel at that moment.
Why do you think this happened? At least one of the emotions generated by the conversation is that of surprise–being confronted with information you thought you should have known (particularly before the person who was telling you), but for some reason, you didn't.