DIVORCING YOUR GRANDMOTHER by Jean Gould (Morrow: $15.95). Kate, married to George, a psychiatrist, is having an affair with Charlie. Charlie is married to Janet, a patient of George. High-spirited Kate loves Charlie's zaniness, in sharp contrast to the stolid security provided by George, whom she has known since childhood. The story begins on the eve of Kate's hysterectomy to remove a cancer. A chance meeting of Charlie and George at Kate's hospital bedside after the operation catalyzes the situation, knocking George out of his complacency and forcing Kate to choose between husband and lover. At the same time, Janet has left Charlie, as a result of therapy, bringing their marriage to a crisis. How these four people react to the changes in their relationships and begin the process of healing is the substance of this first novel. The characters and scenes are fleshed out with strikingly familiar details; Gould has a particularly gifted eye for domestic life. The intimacy created draws us into her world and makes us comfortable there. If only the characters were as intimate. They are as familiar as the people down the block, and as inaccessible. The third-person narrative is solely from their point of view--and since they are curiously shy of self-examination, we learn very little about their motivations. It's not as though these people are interesting enough to carry a novel; they're not. But neither do they, by their familiarity, open up to allow us to discover ourselves in them. This is unfortunate, for their story is worth telling.