JOANNA'S HUSBAND AND DAVID'S WIFE. By Elizabeth Forsythe Hailey. Delacorte. 328 pp. $17.95.

ELIZABETH Forsythe Hailey, author of the splendid tour de force of a first novel, A Woman of Independent Means, and a maudlin, programmatic second novel, Life Sentences, here regains a little ground, although Joanna's Husband and David's Wife still cannot hold a candle to that memorable first effort.

Hailey has done well to return to the sort of old-fashioned literary device she used so creatively in A Woman of Independent Means, which was composed entirely of one woman's lifetime of letters. In Joanna's Husband and David's Wife, the medium is a woman's journal, the "year-by-year history of a marriage," along with the annotations made by her husband, who happens across the journals just after she has left him. Since letter-writing is not the near-universal daily habit it once was, the effect in the first novel was one of distancing and framing: it offered at once a strong sense of period and the making of a portrait. Hailey seems to be attempting a similar effect in Joanna's Husband and David's Wife; but the new "portrait of a marriage" is disappointingly pallid, despite its originality of form.

Readers enchanted by A Woman of Independent Means might recognize genealogical links between it and the new novel, which is in some respects a sequel. (How deep do Hailey's autobiographical sources lie?) These readers will not have forgotten the inimitable Elizabeth Steed Garner of Dallas, Texas, and may even recall her grand-daughter, Betsy, who married a drama student, then shuttled about with him between Yale, New York, Dallas and Los Angeles as he pursued a modestly successful career as a playwright.

Well, Betsy is here reincarnated as one Joanna Scott, sharing the same resum,e and family history, albeit with name changes. Enough obscure dates and incidents correspond in each novel to confirm the link. The overlap, though minor, is interesting, showing us as it does the intersections of certain lives and events from two historically different angles: first, the grandmother's view of an adored grand-daughter, then the grown grand-daughter's thoughts about her doughty old grandmother.

As a matter of fact, the complexity of ordinary family life, along with the need to see things from different points of view, is a major theme of Elizabeth Forsythe Hailey's. In all three of her novels she is at pains to show how "complicated" people are (this is a key word) and how intricately webbed their lives. As Joanna reflects after 24 years of marriage, "David and I had created a family infinitely more far-reaching and complicated than the two daughters who stood beside us . . . , all kinds of cross-connections, personal and professional . . . weaving our lives into a fabric so strong and startling in its colors."

Ironically, this perception of interdependence leads directly to Joanna's further observation that the more relationships of different kinds one enters into -- and "complicated" is taken in this novel as a virtual synonym for mental health -- the more difficult it becomes to relate to just one person, a spouse for example. She broaches this problem in her final journal entry, addressed to her older daughter. "How can I tell you what marriage is like when it is different for everyone, even the two people involved? A husband and wife often come to very different conclusions about the same marriage."

THERE IS NO denying the substance of the theme, then, nor the suitability to this theme of the novel's form. There is nothing more titillating than reading somebody else's private diary (even a fictitious one) and it is psychologically satisfying to be reading over the shoulder of the newly abandoned husband. He does not fail to get in some sharp thrusts, as in his comment on the following very early entry: "David took me to his room. Then we didn't have to talk and everything was a lot better. Later we had hamburgers in front of a roaring fire at a wonderful place called George and Harry's. I love New Haven." David: "Did she ever in her life sit in front of a fire that wasn't roaring? She always saw what she wanted to see. Maybe I wouldn't be in so much pain right now if I'd learned that trick." (David is right about Joanna's habits of thought, as it happens, but since the novel is largely composed of her reflections, this indicates something of what is wrong with it.)

Where the novel really disappoints, though, is in its characterization, which is surprising in view of the variety and saltiness of the characters in A Woman of Independent Means. The word which most readily springs to mind to describe the cumulative impression David and Joanna made on me is saccharine, Joanna in an unctuous, humorless way, David (even worse) in a wimpish, bullying way. There is nothing to suggest that Hailey intends us to see them like this. Rather, the saccharine quality derives in both cases precisely from a fatal lack of distance between the author and her fictional offspring. Neither David nor Joanna comes alive as a real or even a "complicated" person, despite their much-vaunted network of friends and relations. They mostly represent various kinds of modern and not-so-modern ideas jostling for position. This is not to suggest that they are static: each changes and grows with altering circumstances. But even their growth is overburdened with meaning, as, for example, when Joanna becomes a best- selling novelist and David must learn to play her role of domestic helpmeet and second fiddle. Together, they provide a sad contrast to the feisty Elizabeth Steed, that genuinely independent woman, who represents nothing but herself.

The territory of marriage explored in Joanna's Husband and David's Wife is of perennial interest, and Elizabeth Forsythe Hailey is too intelligent a writer not to provoke us frequently into useful reflection, but I doubt whether the characters she has created here will endure long in our memories.