单选题 .  The way people hold to the belief that a fun-filled, pain-free life equals happiness actually reduces their chances of ever attaining real happiness. If fun and pleasure are equal to happiness then pain must be equal to unhappiness. But in fact, the opposite is true: more often than not things that lead to happiness involve some pain.
    As a result, many people avoid the very attempts that are the source of true happiness. They fear the pain inevitably brought by such things as marriage, raising children, professional achievement, religious commitment, self-improvement.
    Ask a bachelor why he resists marriage even though he finds dating to be less and less satisfying. If he is honest he will tell you that he is afraid of making a commitment. For commitment is in fact quite painful. The single life is filled with fun, adventure, excitement. Marriage has such moments, but they are not its most distinguishing features.
    Couples with infant children are lucky to get a whole night's sleep or a three-day vacation. I don't know any parent who would choose the fun to describe raising children. But couples who decide not to have children never know the joys of watching a child grow up or of playing with a grandchild.
    Understanding and accepting that true happiness has nothing to do with fun is one of the most liberating realizations. It liberates time: now we can devote more hours to activities that can genuinely increase our happiness. It liberates money: buying that new car or those fancy clothes that will do nothing to increase our happiness now seems pointless. And it liberates us from envy: we now understand that all those who are always having so much fun actually may not be happy at all.1.  According to the author, a bachelor resists marriage chiefly because ______.