Like faith, marriage is a mystery. The person you're committed to spending your life with is known and yet unknown, at the same time remarkably intimate and necessarily other. The classic seven-year itch may not be a case of familiarity breeding ennui and contempt, but the shock of having someone you thought you knew all too well suddenly seem a stranger. When that happens, you are compelled to either recommit to the relationship or get the hell out. There are many such times in a marriage.