This in-depth look at the gritty truth of contemporary relationships could not have come at a more interesting time. In the current dispute over tax breaks for married couples, the main political parties have begun to engage in what feels like a genuine battle over the status of marriage in modern life. At the same time, we are witnessing a burst of feminist anger at the increasing sexualisation of society.
But the emphasis on the iniquities of object culture - lads' mags, lap-dancing - serves also to remind us of what is missing from modern women's laments: of the continuing muffled silence about structural inequality. It's just too easy to reduce all complaint on this front to a Mumsnet-style rumble of irritation and self- questioning, devoid of grand analysis and empty of calls for political change.
Kate Figes is a seasoned feminist, the author of several books on women's most profound experiences, from life after birth to the difficulties of raising teenagers. She always tackles her chosen subject head-on, never shying away from the more brutal personal truths, yet supremely reasonable and optimistic in her broader outlook. So Couples is neither a how-to handbook nor a polemic. Instead, in her introduction, Figes clearly states her rejection of both retrograde appeals for the return of marriage and an "outdated feminist understanding of marriage as an institution which symbolises the ownership and exploitation of women".
Fair enough; we have, indeed, moved far from the crippling laws and mores that shackled women in centuries past. But is contemporary coupledom really a new pairing of equals, as Figes implies, or are women simply coping more stoically with age-old dissatisfactions? She is
a wonderfully thorough and efficient guide through this complex terrain, drawing on both landmark academic histories of marriage, cohabitation and relationships in general, and her own interviews with people in relationships. She covers heterosexual and gay relationships and draws the "new networks" of family, such as step-parenting, into her generous embrace.
But the core of the book is undoubtedly the personal testimonies of 120 men and women who have spoken freely to the author about everything from sex, infidelity and child-rearing to housework, illness, in-laws, old age and much more. The resulting threads of personal experience - we return to some couples several times within the book - are as absorbing as a good novel or a soul-baring talk with an old and trusted friend.
Figes has said that the hardest part of the interviewing process was getting people to talk about sex. She is refreshingly unjudgemental about some of the unusual arrangements she uncovers, such as the couple engaged in a long-term relationship with another married pair and the woman who takes occasional lovers, with her husband's unalloyed approval. Figes notes, with amused wistfulness, this woman's general air of radiance.
Such arrangements threaten the more conventionally minded, she observes, because they fear similar intrusions into their own partnerships. She is perceptive about the way that popular culture's obsession with the myths of romance presents a hindrance to understanding of what it takes to make a long-term partnership work. Couples themselves don't help; whether through pride, or vanity, or fear, they frequently hide the reality of their relationships from even their closest friends and family. Far from rushing into divorce, most people struggle on for years, trying to resolve their problems.
Figes wisely reminds us that love is work, love is compromise; its long-term success requires honesty, communication and forgiveness. In one of the saddest interviews of the book, a married woman speaks of her inability to forgive her husband's affair of over 20 years ago, while her husband speaks poignantly of his wish to heal the rift.
So is modern coupledom a fairer bargain for women? Figes, while genuinely honest about the challenges of making even the happiest of relationships work, takes a resolutely upbeat view. Women are gaining more economic freedom and power, and, contrary to all the doom and gloom about broken family life, the modern couple are in pretty good shape.
I wonder. To me, the testimony in Couples resounds with a persistent bass note of male selfishness and female dissatisfaction. For every story of a couple who have struggled to achieve a reasonable balance of power, there are numerous examples of women who have sacrificed ambition or freedom, in the most ordinary of ways, in order to achieve stability, largely for the sake of their children.
My niggling concern at these elements drew me back to the work of the Australian feminist Susan Maushart, whose hard-nosed, splendidly bad-tempered stock-taking of modern marriage, Wifework, was published nearly a decade ago. Maushart argued then that marriage remains a deeply unbalanced arrangement, designed for the female to provide "maintenance of men's bodies, minds and egos". However, she came to believe that divorce is worse for children than most kinds of marital discord, and concluded that men and women should accept that "marriage entails a sort of base level of unhappiness that couples need to learn to anticipate and accept".
Figes would recoil from quite such a bleakly summary judgement. And rightly so: a happy partnership can help ground us in an uncertain world. Interestingly, however, her final prescriptions for family life are remarkably similar to Maushart's. She, too, believes that women should demand more domestically of men, and sensibly suggests that we should all contemplate the reality of divorce or separation sooner rather than later in our relationships. Only then can we come to appreciate the limits and possibilities of what we have chosen and have a shot at common happiness. Only then do we have the chance to make the best of an undoubtedly difficult, if not always bad, job.
Couples: the Truth
Virago, 416pp, £14.99
Melissa Benn's most recent novel, "One of Us", is now available in Vintage paperback (£8.99)