The organ music dies, dramatic vibrations vanishing upwards into ancient wooden beams and distant white plaster. The church is hushed and the packed congregation still after its vocal exertions - "I Vow to Thee My Country" - save for the singsong babble of one lone child, sullenly indifferent to her mother's rage and her father's studied glare.

It makes no difference to the bride (beautiful) or to the groom (bashful). Even this far back, in the very last pew, far from the altar, apart from the crowd, their mutal rapture is as obvious as the first blooms of spring: a riot of rich, unrestrained colour in a world sensibly dressed for bad weather.

Hear this: the vicar booms something serious about sacred commitment, and small Genevieve tilts her head to tall Richard and, ohwhatarush, utters the oaths, vows the vows, he swiftly, tremulously following tongue- tied suit: love and honour, sickness and health, for richer and poorer, for as long as they both shall live.

And I have this sore whatever feeling, an indefinable emotion that is both amused and bemused. For I am never more moved by the spectacle of heterosexuality, the ritual performance of the "normal" than now, in its falling hour. This is marriage, with the odds baldly against it (check the divorce figures, the swelling numbers of single-parent families, the fading away of the father, how the terrorist demands of the workplace are detonating the nuclear unit), blithely going about its business; a dead man walking. Its blind optimism in the face of brutal fact - that the old structures of hearth and home and a woman's place and what a man's gotta do are demolished - wrings my sentimental, homosexual heart, no matter the institution's cruel and unusual treatment of inmates (women and children first, but, yes, straight men, too) and its long, historical hostility to those who simply couldn't, or wouldn't, wear its tight fit. People like me. Perhaps people like you.

Yet I can remember a time when I yearned for wedlock and what it represented: oh, to stand by my man. Well, we gay men are constitutionally drawn to illusion and wasn't marriage the mother of all illusions: a (broken) promise of belonging amid a world of apparently permanent storm? I thought the pieces of paper, the public utterances, meant more - signified more - than hot words whispered, and half heard, in the dark.

I was wrong. But how could I have known then that "their" system - your system - was about to collapse? How could I know that the culture was about to be covertly and overtly queered (pop goes pansy, chic goes lesbian, men go new) in a thousand direct and indirect ways? And how could I know that the emotional arrangements I and my consenting partners pioneered - everything from serial monogamy to satellite relationships to unfettered sexual freedom - would be greedily welcomed by a re-routed mainstream that had previously despised/denied/looked askance at such "anti-social" options? Adopt or die: there I lay, lost in my envy, never once considering that monolithic heterosexuality might have been gazing longingly at homosexuality's multiple choice all along; gayness, your flexible friend - your generally unacknowledged flexible friend.

Of course, with typical perversity, it is only now, with marriage a lost cause, a wreckage and a ruin, an abandoned role model in need of support no matter from which quarter, that some conservative faggots feel compelled to ride to its rescue, just as wicked, wise Gore Vidal, as far back as 1974, predicted they would. So Andrew Sullivan, author of Virtually Normal, argues that by capturing this citadel we capture acceptance. By acceptance he means, I imagine, legal rights and - it's a curse - respectability, the deceptive dream I once dreamed, and others still do. Hence next week's Netherlands' vote on marriage for same sex couples. Hence the popularity of gay blessings and commitment ceremonies. Slippage: you moving closer to us, us moving to you, to merge in some yet undefined middle. Or muddle.

Politics has its agenda - respectability - and the heart has its reasons: romance. As the vicar's voice announces that this is Genevieve and Richard's biggest step, I swallow the lump in my throat and, think, no, it's not a step, but a leap. A leap of faith into a future you imagine you have mapped out but have not, because no one any longer can. No guarantees, simply a wish upon a friendly star. Like those hot words spoken in the dark, no more, no less, despite the trappings.

And sitting here I suddenly realise why I would still stand up and publicly plight my troth. Today marriage itself is rather gay, too. If it previously pretended to absolute certainty, it currently encapsulates ... this passionate chaos. The sure thing is now a long shot, a bet only a compulsive gambler would take. And that reality is almost as compelling as the stifling illusion it replaces, inadvertently in tune with a sensibility that seized its moment of joy when it could, realising everything was against its survival, that the fragile flame of desire could be snuffed out by an uncaring world, and should be celebrated while it burned hot and fierce. Marriage is now less a belonging, and more a longing, and longing calls to longing. This still nominally straight establishment is calling to me.

The groom is invited to kiss the bride, and he does, sweetly. The congregation gets to its feet. Applause erupts: honest appreciation for their daring. That's it - daring. For what was once common is now different; it requires a little bravery. The kiss goes on. And on: for so long, in fact, that one could fool oneself it was that most ephemeral of things: for ever.