It is hard to know what one may expect to learn about gay marriage, or any kind of marriage, from a wealthy Republican couple drawn, with Mr. Rudnick's customary impishness, from the pages of W. Tibby McCullough and her perpetually self-regarding lawyer husband, Jack, could be William and Pat Buckley. Or Tommy Kempner and his late wife, Nan, the Nouvelle Society hostess who never had an unkind thing to say about anyone -- well, almost no one.