Why is it so hard for some people to communicate?
If you're a good, true friend, you understand and empathize with a person's highs and lows, joys and sorrows, victories and defeats. Just being there is great support to a person you cherish as an important part of your life.
But nothing positive is going to happen if one of the people in the relationship is unwilling to communicate. NOTHING.
Communication can be verbal or nonverbal. Shutting out people may be a coping mechanism, but it is nothing but destructive for both parties. At least answer a question if you are asked. It can be a simple one-word answer or a certain "look", but ANSWER. Damn, it's really not that hard.
If you are trying to punish or drive away the other by not communicating, then maybe you aren't really good friend material after all. Think about that for a while.