Modern Love
by Marcus Collins
Atlantic Books £19.99, pp336

When it comes to intimacy, history is hopeless. What survives of us, mostly, is not love, historical documents being concerned with the political rather than the personal, with institutions far more than couples. The sound of the bedroom door slamming loudly in his ears even before he puts pen to paper - this is a point Marcus Collins readily concedes. But as he also notes, acknowledging difficulty is not the same as accepting defeat.

Unruffled by the lies people tell about their sex lives, and unimpressed by the myth-making that surrounds, say, Seventies feminism, in Modern Love he bravely attempts to chart the changing expectations men and women have brought to their relationships over the past century. I say bravely; successful books, like healthy marriages, involve more than mere pluck.

Collins begins his survey with the ideas of Edward Carpenter, the gay socialist famed for his championing of sandals and for touching E.M. Forster's bottom (an electrifying moment for the latter, if not the former). In 1896, Carpenter published an essay titled 'Love's Coming of Age'. Its premise was simple but, for the time, outlandish. The Victorian system of separate spheres had caused 'maximum divergence' between men and women, with the result that each approached romance with false expectations.

Man's work fetish meant that he never learnt to love and so fell into it, like a 'fly in treacle'; woman harboured a dream of being 'folded into the arms of a strong man and surrendering herself... to his service'. Once married - and their respective hopes thwarted - most couples settled down into a state of 'dull neutrality' towards each other.

Carpenter, full of beardy-weirdy good intentions, thought this a bad state of affairs, and his solution - the closing of the chasm through a recognition that men and women were not so different, after all, and would get along just fine if only allowed to - is one that Collins takes up enthusiastically.

He calls it 'mutuality' and his interest lies in seeing how it fares when set against key moments of social change: the enfranchisement of women; the rise of mixed youth clubs in the 1950s; the permissive Sixties; the angry onslaught of second-wave feminism.

This approach is, however, an unsettling business. Oddly, for a book about intimacy, Modern Love is often almost entirely human-being free. Worse, much of what it uncovers is depressingly familiar. Has so little changed? Is 'dull neutrality' really so inescapable? So it would seem.

Collins is at his most unengaging when doggedly logging the infinitesimally small shifts in opinion within, say, the Peckham Rye Women's Liberation Group ('Dungarees! Political badges! The right not to caress our husbands on demand!') or among starchy radical feminists prior to the outbreak of war in 1918 ('Passion addles reason! Lust nullifies love! Sex is dirty!').

He is at his best when he gets back to basics and allows us to hear the voices of ordinary women and men for ourselves. An exhaustive rifle through the case notes of marriage guidance organisations in the 1950s, for instance, conjures up poor Mrs Robinson, who felt that to have sexual feelings for her husband would be tantamount to 'going mad' and, sadder still, Mrs Jenkins: 'He tries to help me get there with his hands, like they said you should, but it's no good - makes me feel worse - and when he falls asleep I could scream!' (Poignantly, Mr Jenkins was no happier: 'I love my girl and it's awful to see her left in that state and to know I'm responsible.')

Modern Love's sweep ends somewhere in the 1990s. Bridget Jones is obsessing about her weight; Miles and Anna are tearing one another to pieces in This Life.

The cult of the individual, the author believes, rather did for mutuality because 'the assertion of self-interest invited a self-absorption verging on selfishness'. Couples' idea of commitment, he writes, 'excluded much of that sense of obligation without which it remained shallow and brittle'. This is, I think, unfair. Consider the misery many couples endured early last century (misery that Collins does his best to exhume) and it seems perfectly natural that those looking for love might set their targets soaringly, impossibly, high.

Once, the only thing worse than a rotten marriage was not to be married at all. Now, at least, it's the other way round. That's a kind of happy ever after in itself.