I love this little thought from Alain de Botton.

“At the heart of sulk lies a confusing mixture of intense anger and an equally intense desire not to communicate what one is angry about. The sulker both desperately needs the other person to understand and yet remains utterly committed to doing nothing to help them do so. The very need to explain forms the kernel of the insult: if the partner requires an explanation, he or she is clearly not worth of one. We should add that it is a privilege to be the recipient of a sulk: it means the other person respects and trusts us enough to think we should understand their unspoken hurt. It is one of the odder gifts of love.”