In recent years, we have seen a proliferation of self-help books. I applaud this trend,"" says Livsey in her preface. An ominous start. And, as if to confirm our skepticism, she proceeds to employ every convention of the self-help business--quizzes, case history, list-making, the lot--to make what would otherwise have been a perfectly good point, to wit: when dealing with marital problems, one should treat the family rather than the individual. Here's how to deal with everything from a drinking spouse to stress and a subsequent migraine headache. . . from the initial pairing (married or not) to the twenty-year itch. And not one new idea in the bunch.