JUDITH ROSSNER sits curled in a puddle of sunlight, an improbable prophet of gloom.

One might expect the author of "Looking for Mr. Goodbar" and six other novels of heartsick marriages and misbegotten trysts to be a dark-browed brooder enshrouded in woe. But at 48, the Bronx-born writer is a blithe and iridescent presence, with bright turquoise frames on her glasses ("I think they're smashing"), a canary-yellow watch on her right wrist (left-handed? "No, I'm left-eyed") and the giddy nimbus of hair once known as a Full Erica Jong. Newly separated from her second husband, newly celebrated for her latest novel, "August"--the promo trek for which has perched her on a sofa at the Mayflower Hotel--she's mistakable even at close range for a boutique-foraging, kaffeeklatsching missis from deepest Scarsdale.

But the medium is at odds with the message. For decades, in life and fiction, Rossner has been plumbing the emotional deeps and dark, needy sumps of the female soul as it struggles to find a worthy mate. In her books, the prognosis has never been good. And her latest report is grimmer yet: "There's a cycle going on now in which misogyny is a very strong factor," she says. "For a variety of reasons--including women's increased availability--more of those feelings are coming out than when men felt more protected."

Protected? She tucks her calves up against a thigh, drops a hand down to hold her foot, and leans back into the subject. "The subjugation of women, of blacks, of anybody is designed to protect someone." And men "wouldn't feel the need for protection if there were no fear. There is no such thing as simple male chauvinism--that just doesn't exist. Those things were designed to counteract men's fear of being dominated by women, that women were better or stronger or could make babies.

"Men's fear of women, of women's sexuality, became worse when women had the lure of the forbidden." But when "women became available and then terribly eager for a variety of reasons--including those who were sold a bill of goods about a career being everything and eventually realized it wasn't," then men "know this and they feel when they are being used or put up with.

"And it's astonishing what some women will put up with just to have a warm body--some of the brightest women I know are just obsessed with that search. It's very sad."

It's also her habitual subject. From the three novels preceding "Goodbar," the shocking 1975 best seller, and continuing with "Attachments" (1977) and "Emmeline" (1980), Rossner says, "my abiding theme is separations." Her women typically yearn to merge, through men or family, into an enfolding sanctuary of love. But that haven proves false or unreachable, and most of her books "are about whether the heroine should leave--whether it's a husband, a mother, a home." Those with low self-esteem remain to suffocate in indifference; "people who value themselves are more likely to leave."

So it is with "August," set in the exotic couch-lands of psychoanalysis, late-'70s-style. It begins when a winsome, disturbed teen-ager named Dawn Henley arrives at the Manhattan office of analyst Lulu Shinefeld. Dawn, worried that a recent auto accident may have been subconsciously self-inflicted, turns out to have a brain-load of neuroses that would send Freud himself lurching for the Bromo: Among other derangements, she's a hypersensitive orphan raised by a lesbian couple and morbidly desperate for parental security--a need she first satisfies and then outgrows at Lulu's compassionate hands.

A second, occasionally comic plot line follows Lulu (like Rossner, a divorced mother of two during the '70s and "exactly my age") through her travails with two husbands (one a vagrant cad, the other an oblivious lump), her soulful and volatile affair with Charles, a sympatico married analyst, and her agonizing attempts to master loneliness and lust in a society in which ladies over 40 are in ever-diminishing demand.

"That age for women," Rossner says, "has social problems it doesn't for men. The reality is that a large number of men are so afraid of death--connected so closely in their minds to birth and therefore to women--that after a certain age they cannot deal with women who are their peers." She speaks in halting spurts of words--pausing, it seems, less for felicity of phrasing than precision of feeling, like talking to a psychiatrist. With each new thought, she moves her hands to touch a different part of her body--as if in this anonymous hotel room, bereft of context or consort, there were some doubt of her existence.

"The only men in the world who are interesting are those who have not been so frightened of the female part of their identity as to throw it over completely and are able to once in a while identify and understand. Which is the appeal of someone like Charles in the love affair with Lulu," she says.

If some male readers find Charles a dithering wimp, Rossner offers this: "My friend Molly Haskell, the film critic, says 'Men never understand why Woody Allen gets the girl. But the women do.' Women always like the men in my books--men think they're jerks sometimes. They don't know why they go for them. It's because women put up with more in men than men put up with in each other." And the ultimate question in "August" becomes whether Charles, despite his fluoroscopic insight into Lulu's feelings, is too much to put up with.

It will be decided without rancor or man-hating. "There's no question that the whole macho refusal to understand or be interested in that world of feeling has to do with fear, and not with anything that's innately masculine," she says. And if that's anathema to the more dogmatic feminists, well--a flare of sudden contempt--"they're just a bunch of middle-class, theoretically radical women going around telling others how to live."

Dawn's story, which makes up most of the narrative, is told in serial retrospect through dozens of scrupulously detailed scenes from her analysis--scenes The New York Times Book Review called "eerily authentic" in their meandering dialogue and therapeutic rhythm.

"Obviously, I've been in analysis," Rossner says, crossing her arms on her chest. She went first as a teen-ager: "I was a middle-class juvenile delinquent at the beginning of the '50s. Ten years later, nobody would have bothered--all middle-class kids were juvenile delinquents."

How did the daughter of a textile official and a warmly supportive schoolteacher ("my mother wanted me to be a writer--she used to say magazines were my favorite toys") end up a premature hippie? "I can't. I really can't." At any rate, "I got straightened out," became determined to write, entered City College, and in 1954 promptly dropped out at 19 to marry Robert Rossner, an idealistic teacher and writer. Why so young? "I don't remember why I got married either time, actually." She went to work in the ad department at Scientific American, but "I started to get all excited about it and realized I was never going to get my book written."

So "I took a speed-writing course and took a job in a real-estate office, bored out of my mind." It worked. "I wrote my first book, then I had a kid. Then I wrote a book, then I had a kid. I get children and divorces after I finish books. That sounds very callous--I like to make myself sound tough sometimes. The truth is that when I'm finishing a book, I become absolutely absorbed and nothing else commands my attention. Last year, for example--at the end of my second unfortunate, unreasonable marriage--I was working 7 days a week, 12 or 16 hours a day. It was only when that ended that I took steps to make my life reasonable again. Did I say reasonable? Do you have a euphemism-of-the-week award in Washington?"

Her first efforts, paperback originals, attracted little attention; but she never felt failure. "No! My first book took five years to write and I made $1,000 on it and I was in heaven. The second took three years and I made $3,000. All this time I was a housewife being supported by a husband. I was very lucky--my husband wanted to write, but he couldn't afford to." Then everything changed. "At the end of the '60s, my husband decided that we should leave--drop out and go to a free school setup" in rural New Hampshire.

"I fought and then I gave in. It was that whole middle-class fantasy about giving your kids the right values." (Lulu's first husband, Woody, is a philandering, folksinging Stalinist.) The former Bronx delinquent found herself unsuited to living off the land and hungry for New Yorkers. "Even the drop-outs were from Boston! It was the end of the marriage."

She returned to Manhattan, where she has lived since 1971, and took a job as a secretary in the psychiatry department of a hospital. Her third novel, the aptly titled "Any Minute I Can Split," was published in 1972, and "I began to feel silly as a secretary. I was 37 years old--it was like being in drag. I wanted to support myself by writing. I started 'Attachments,' but I thought of that as an entirely uncommercial book and put it aside.

"But then Nora Ephron was doing a woman's issue of Esquire, and she asked if I wanted to do something." A 27-year-old teacher named Roseann Quinn had just been murdered by a man she met in a singles bar, and Rossner, intrigued ("was she looking for her own death?") agreed to write it up. Her mood was right: "I had just had a car accident and burned my leg and I was all depressed and everything."

But ultimately Esquire's lawyers killed the story. "I said, 'Fine, I'm a lousy journalist anyway.' Which I am. I have the absolute urge to bend reality to my own needs. The facts are my enemy. So I figured I'd do it as a novel."

With a $5,000 advance and hopes for a paperback sale, "my idea was that I would make just enough money to not be a secretary for a year." Because of the job and "two young children at home, I got up at 5 and wrote until 7 for a year."

The result was a best seller, a movie, and a gigantic threat to Rossner's sense of self. "By this time I was in another analysis because I was concerned with how I cracked up the car that got me into this thing."

She bought a house in Croton-on-Hudson that "represented safety to me. I was afraid of losing my identity in the fame-and-fortune mill. Part of it was having lots of people who wanted to know me, wanted to give me something or get something." Part was the review process, although "I've only once been savaged a review of 'Emmeline' in The New York Times Book Review and I did feel very publicly exposed and humiliated."

On the tour for "Goodbar," she returned to "Attachments" and "took my notebook with me--I work by hand on the first draft--because I had a conscious feeling that I wanted to hold onto the thread of my life. And I took Flaubert's letters because that's about being an uncompromising artist. Someone to look up to, a god to fit my needs."

She first conceived of "Attachments"--about two women married to Siamese twins--because "I had this remote thing about twins. I'm sure it all originated with the Bobbsey twins in my childhood--the notion of utter togetherness and wholeness. The thought was that women can only achieve through a man in their adult lives what everyone began with--the kind of oneness and ecstasy one has as a preborn or infant with the mother."

After "Emmeline," based on the true story of a 19th-century cotton-mill girl who defied solitude and found a terrible kind of love, "August" had "a much more disorderly genesis. It began as a love affair between Lulu Shinefeld and a male writer from one of my early books. I went through about 120 pages of that and then one day in August about two years ago I looked at my typewriter, said, 'I'm bored,' and went to sleep. When I woke up in the morning, Dawn just sort of walked into the room. That's facile, but it's absolutely accurate."

The narrative is interspersed with Lulu's ideas for articles. Rossner calls them "a chance for me to sound off a little in ways I don't usually" about men, sex and society.

One paper would argue that guilt and anxiety over food consumption has become to the liberated lady of the '80s what sex was to her Victorian counterpart: "anorectic disorders were the 20th century's abortion on demand for the large number of young women to whom sex (or abortion) was no more optional than three meals a day had once been," and "swelling and protrusions were now the betraying symptoms of the greedy."

Another speculates that men's libidinal urges are determined by custom. "A certain number of men's sexual appetites seem to have diminished in proportion to the increased availability of women," Rossner says. But unfortunately, "many women now seem to be obsessed with sex as it has become increasingly unavailable."

How can she know? "I love gossip, and I'm the repository of all my friends' secrets. Oh God, I know everybody's affairs and everything. But they never get into my books . . . soon. Always later and unrecognizably." Among her close friends she counts writers Haskell, Barbara Seaman, Lois Gould and Nancy Milford; male friends usually come from business or academe.

For her next book, she's considering "one on Emmeline's son maybe. And one that's creeping up on me. It's about people I don't like," a respite from her habitual industrial-strength empathy: "I end up liking and caring for and identifying with almost everyone in my books."

But first the tour, then back to Manhattan, where she lives alone now. Her daughter, 23, is married; her 17-year-old son lives with his father. So in eight rooms on West End Avenue, "I'm just a hausfrau. I cook, I garden." And despite a penchant for snorkeling, she rarely wants to travel.

But not really alone: She wrote much of "August" at a privately funded collective office space called The Writer's Room. When her time expired, she found "a few of us had formed such a family in that room, become such a tight group, that we couldn't give it up." So she and seven other women have rented their own space and work together in one big room.

Oneness. Attachment. Togetherness. And no males need apply.

"Well," Rossner says, laughing in pure earnest, "I always say I'm only heterosexual from the neck down. My brain is with the women."