It’s tempting to think of marriage as old fashioned. Why not just live with someone and be done with it? What need for a public ceremony? Why the weird traditions all those churches, temples, hymns, vows and prayers? Marriage must be a silly relic from the religious childhood of humankind, not designed for the more logical modern world. And yet it survives. The essence of marriage is to tie our hands, to frustrate our wills, to put high and costly obstacles in the way of splitting up. Why do we do this? Originally, we told ourselves that God wanted us to stay married. But even now, when God is not invoked, we keeping making sure that marriage is rather hard to undo. For one thing, you carefully invite everyone you know to watch you say you’ll stick together. You willingly create a huge layer of embarrassment were you ever to turn round and admit it might have been a mistake. Furthermore, even though you could keep things separate, marriage tends to mean deep economic and legal entanglements. You know it is going to take the work of a phalanx of accountants and lawyers to prise you apart. It can be done, but it will be ruinous. It is as if we somewhere recognise that there might, rather strangely, be some quite good, though uncomfortable, reasons why making it difficult to split up a union can be an advantage for its members. The Marshmallow Test was a celebrated experiment in the history of psychology designed to measure children’s ability to delay gratification – and track the consequences of being able to think long-term. Some three-year-old children were offered a marshmallow, but told they would get two if they held off from eating the first one for five minutes. It turned out a lot of children just couldn’t make it through this period. It was too tempting; the less immediate benefit of gobbling the marshmallow in front of them was stronger than the strategy of waiting. Crucially, it was observed that these children went on to have lives blighted by a lack of impulse control, and fared much worse than the children who were best at subordinating immediate fun for long-term benefit. Relationships are perhaps no different. Here too, many things feel very urgent. We’re angry and want to get out. We’re excited by a new person and need to abandon our present partner at once. And yet as we look around for the exit, every way seems blocked. It would cost a fortune, it would be so embarrassing, it would take an age. This isn’t a coincidence. Marriage is a giant inhibitor of impulse set up by our conscience to keep our libidinous, ungreatful, wild, desiring selves in check. What we are essentially buying into by submitting to its dictates is the insight that we are (as individuals) likely to make very poor choices under the sway of strong short-term impulses. To marry is to recognise that we require structure to insulate us from our urges. It is to lock ourselves up willingly, because we don’t trust ourselves. It’s a very unusual marriage indeed in which the two people don’t spend a notable amount of time fantasising that they weren’t in fact married. But the point of marriage is to make these feelings not matter very much. It is an arrangement that protects us from what we desire and yet know (in our more reasonable moments) we don’t truly need or want. At their best, relationships involve us in attempts to develop, mature and become ‘whole’. We often get drawn to people precisely because they promise to edge us in the right directions. But It is too easy to seem kind and normal when we keep going out with someone new. The truth about us, on the basis of which self-improvement begins, only becomes clear over time. Chances of development increase hugely when we don’t keep running away to people who will falsely reassure us that there’s nothing too wrong with us. Over time, the argument for marriage has shifted It’s no longer about external forces having power over us: What we are correctly now focused on is the psychological point of making it hard to throw it all in. For the last fifty years, the burden of intelligent effort has been on attempting to make separation easier. The challenge now lies in another direction: in trying to remind ourselves why immediate flight doesn’t always make sense; in trying to see the point of holding out for the second marshmallow.