The fact is that by its nature love has never been and cannot be susceptible to a single precise definition,"" the therapist-authors chorus; but from there it's only a few flips of the page to their ""six basic styles of love,"" with all the trimmings and permutations thereof. The most ideal couple relationships, we are told, occur between those who score high in both ""Best Friend"" and ""Unselfish"" categories on the 50-query ""Love Scale Questionnaire""; that's because both styles stress ""giving"" and the anticipation of the other's love needs. Love as popularly defined seems to embrace Romantic and Unselfish tendencies; Romeo and Juliet succumbed to this classic combination. Game-playing, Possessive, and Logical--meaning practical--styles complete the roster, but all to no avail: this is for fortune-cookie analysts only.