Money can't buy you love, but can a loving relationship equate to a cash bonus? new research from the university of london puts a price tag of £53,833 per annum on marriage and a rather higher monetary value - £82,500 - on living together in a study on the factors influencing happiness. So why the discrepancy in value? "The difference is puzzling but over time, couples moving from single status to living together seem to make a greater leap in happiness than those getting married," says the report's author Dr Nattavudh Powdthavee. It is interesting that cohabiting rated higher in the happiness stakes than marriage, since in Northern Ireland there has, until fairly recently, been quite a stigma attached to couples' living together without being married.

But attitudes are changing - in the past decade there's been a cultural shift away from automatic censure of cohabitation to tolerance. Even the Church of Ireland has caught up with the new morality, with Alan Harper, the new Archbishop of Armagh, describing committed partnerships as not exactly the same as marriage "but worthy of respect".

And the statistics support the zeitgeist, with numbers of marriages here falling from 8,576 in 1995 to 8,140 in 2005. When the last census reported in 2001, it found 53,000-plus couples living together and 649,000 couples married or remarried.

Jane Conaghan (nee Hardy), in her forties, married to Michael (45), is wholly for matrimony. They live in Belfast. She says:

Four years ago on June 20, my now husband and I took a short walk through Canterbury, from the functional registry office to the far from functional crypt of Canterbury Cathedral to have our wedding blessed. Fondly imagining ourselves like a couple of Thomas Hardy characters (not the doomed ones, obviously) with a couple of bridesmaids and a number of friends in tow, we were heading towards the state of holy matrimony.

We had taken a lot longer than the half an hour's stroll to get this far. As one brother-in-law sarcastically commented, we hadn't exactly rushed into wedded bliss, having been an item for some 12 years and having lived together for about nine. What made us want to spend several thousand pounds on a big party on an admittedly glorious day, with around 80 close family and friends, and what changed in our relationship that Friday?

Apart from rather liking the new identity of Mrs Conaghan, I think the impetus to change status and form of address grew in part from a sadness. We needed some marital joy as the grim reaper had been kept pretty busy in our families the previous year. My sister and mother had died within five months of each other and, perhaps understandably, the grieving process included the desire to cling on to the remaining members of the tribe. It was a primitive instinct, a need to hammer in the tent pegs - and tether an admittedly pretty secure other half. The result was a resounding G major chord in our lives that I don't think you can put a price on - as my nephew said to me that evening, on the beach with a sunset straight out of Turner: "Great day." Which it was. Michael didn't get down on one knee to propose nor did he produce the cliched small diamond square cut ring from a box. In fact, we bought the ring together a week after we'd had the chat. But something in the air had changed, irrevocably, and it felt good. As soon as we had agreed to get married - I seem to remember the choice of day unromantically depended on Michael's working schedule, with him ringing me excitedly to say he'd booked the time off, finishing the call with " Thunderbirds are go ..." - things began to alter. There was a new courtliness, a not taking things for granted - maybe in all the years of cohabiting, we'd got slightly casual.

Routines, and we are the sort of couple that indulges in lots of small, silly routines, were re-thought. We wrote each other more notes, looked at each other with, I suppose, new eyes. I got bunches of flowers more frequently, he got more M&S chicken Kiev for dinner - his favourite, but not mine. We discovered new significance in the significant other, if you like. Any troubles that surfaced, including another close bereavement, were faced in the knowledge that we were becoming an official team - the private commitment was now made public and stronger for it. Our unusual honeymoon, which involved a dental abscess (mine), trips to emergency dentists and a hot week at home watching the Glastonbury Festival and Wimbledon on the box while ingesting strawberry smoothies and later, swimming in the sea, was enjoyable, even ecstatic, whereas had we had a comparable week's holiday marked by illness pre-marriage, we would have been complaining all the time. So a kind of grace, ie strength under pressure, a hand to hold permanently - and did I mention decent rumpy pumpy? - that's married life."

Esther Haller-Clarke (33) is mum to Olivia (8), by a previous partner, and Lola (seven weeks) with Darren Richardson (41). They live in Belfast. She says:

It's unsurprising that this research says living together is worth more in terms of cash value and contentment than marriage. I would definitely have expected that finding in this day and age, especially if you own your own property together, which is as big a sign of commitment as getting married in my view.

It's almost like agreeing to go into business with someone. And, in cynical terms, it is as difficult to get out of as marriage. I would have maybe expected the report to indicate a bigger sense of security in getting married, although I personally don't feel that. We have children, and that commitment is definitely as strong as any marriage.

What makes me happy in this relationship? How long have you got? The repercussions of the relationship itself, good communication, a good love life - that's a prerequisite, and after all, it's a relationship with my partner not my brother - and a sense of humour. Of course, the older generation say they would be happier if we got married. I started hearing the phrase 'marriage makes things neater' a lot when our second daughter was born recently. If I'm honest, sometimes I do feel that, and sometimes I don't. Darren and I have known each other for 13 years, I was a young lass of 20 when we met and in no mood for a committed relationship. Darren is eight years older, so he was ready. We met in Leeds, then I moved to London, and we only met up again four years ago. My first daughter isn't Darren's.

At this stage, if we did marry, it would be to show that commitment in front of friends and family. But how much more committed can you be? Of course, when you're in a relationship for a period of time, with a marriage certificate or mortgage, life can take over, and you have to make an effort to go out to dinner and keep the magic alive.

It's very easy not to bother, especially with a baby. You think, 'can I be bothered to get dressed up and go into town?' When I had Olivia at 25, I felt I was missing out on my social life, but I don't feel that at all now. Socialising has changed for us, the children come with us and we stay over with friends.

Do you have to make more of a concerted effort in a partnership? No, it's more about the longevity of the relationship. Darren and I really like music and, on a Friday, we'll sit down and have a nice bottle of wine, switch off the TV and get out different CDs - the genre is immaterial as long as the music is good. We'll be saying, 'no, no, listen to this one' and start telling each other stories.

Darren has managed a few bands, and I've done arts marketing so we listen to stuff right across the board. Darren now works for Bang & Olufsen, and sometimes we road-test equipment. In my set, there's a slight trend towards reverting to marriage, but people are marrying later. It's more the try-before-you-marry ethos.

Would I like to get married? In terms of our family, it would make things easier, as I and the two girls have my surname, and we'd all take Darren's name. We'd probably do it to make our parents happy. I'd lose the lovely pretentious surname Haller-Clarke though, which would be devastating.

We've done things back to front in our parents' view, but our parents are pretty tolerant of difference. They've let us go out into the world and make our own mistakes. In a way, there's too much choice now, and if you feel you can easily get out of a relationship, where's the incentive to work at it? I have friends who have walked up the aisle thinking, 'if it doesn't work out, I can get divorced'. I might go out and get married tomorrow, who knows, but it isn't a huge priority. I certainly wouldn't want to be a naff 40-year-old bride. In my ideal world, I want to get married only once - I haven't ruled it out, but it's not something I need to do."

Jane Graham (35) is married to Paul McNamee (34 ). They have two children Anne (4) and Johnny (seven months) and live in Glasgow, having moved there from Bangor. She says:

I've always enjoyed male company. I was close to my dad growing up, and spent many nights sitting up until three in the morning with him, arguing about books, films, politics and football. When I left home I shared a flat with girlfriends but it wasn't ideal - queuing for the bathroom, compartmentalising the fridge, arguing over tiny amounts of money and whose turn it was to commandeer the TV was no fun. And I found that it was difficult to replicate those long conversations about the stuff of life I'd had with my dad - girls don't do them as well, often considering them 'anal', and preferring to discuss diets.

When I met a boy I got on very well with, and decided there was probably at least a good year in the relationship, I moved in with him. I've since lived with four men, three of whom I knew from the start that there was no chance of marrying or having children with. It didn't matter - I just liked watching TV on the sofa with them, going to bed and waking up with them, having someone at home to vent at after a hard day, and celebrate with after a good one. All of the men I've lived with have liked music, good food, socialising, Woody Allen, Bob Dylan and talking, talking, talking - they've made me laugh and hugged me when I needed it. In terms of my general happiness, I've been far more content while living with them. I've also been richer - two salaried people splitting bills and rent, with two sets of families and friends to call upon for help, makes life easier and cheaper.

Alone

I lived alone in London for a couple of years between men. It sounds lonely but I always found London a huge buzz and there were occasions, when I craved privacy and autonomy. But too often I felt the emptiness of a house that was always dark when I came home from work and which never smelled of coffee when I woke up at weekends. Being burgled didn't improve the experience. When I finally met a man that I really believed I could have children with (I had a hunch the night I met him, in the beer tent at Glastonbury festival) I eagerly moved in with him after a couple of months. This time it felt different - the relationship was serious, possibly signalling a huge change in the direction of my life. Then, in my late twenties, I found it very exciting. When he asked me to marry him I was delirious with happiness. Living together became a statement of intent; we didn't want to be apart - ever again. Sharing that knowledge as we planned our future was a delight. We were also financially better off than we'd ever been. We were earning well in London, working in the music business and enjoying a very busy, glamorous social life. Things were good. So good, that we decided to try for a baby before we got married (it suddenly felt more urgent) and our daughter was born 10 months later. The ultimate commitment, she bonded us together, I felt, more tightly than any piece of paper ever could. But we were still keen to get married and I'm glad we did. For one thing, we had a fantastic day, where fathers, brothers, friends, bride and groom stood up and said some profound,unforgettable things to the people we loved - things we might never have had the courage to say without the occasion as an excuse. We brought our families together for the first time. We held on to each other more tightly than before.

Three years on we're still extremely happy together and proud of our little family (we added a son last year). We're less well off - marriage tends to be expensive, as you're more likely to do things like getting a mortgage, having kids and buying a reliable car. But our family laughs and plays together, and we all sleep worry-free. And if anything difficult does happen in the future, I'm not afraid - I know I won't be going it alone."