'I KNEW I was lying at the altar when we took our vows, I knew I didn't believe that it would be just us from then on and I think she knew too, we bought into the idea that marriage would put us on the straight and narrow," James*, 36, tells me as he shows me his wedding photographs.
Five years later James and his wife have separated and James has deep regrets.
"I wish we hadn't tried to conform to the idea of monogamy, it's an unreal and unnatural thing, I wish we could have just understood each other and forgave each other, it was the endless sneaking around that finished us."
As relationships crumble under the pressure to conform to the 'happy ever after', more and more people are turning their backs on the Cinderella fantasy and are realising that no relationship is flawless. Sienna Miller caused controversy last week when she announced that she thinks monogamy is overrated. The star was reportedly heartbroken when her on/off boyfriend actor Jude Law admitted last year that he had an affair with his children's nanny.
Today, Sienna's outlook has changed dramatically. She told Rolling Stone magazine: "Monogamy is a weird thing to me. It's overrated because, let's face it, we're all f**king animals. The fact is, no one is perfect."
For James and his ex-wife, who have a five-year-old daughter, life was less than perfect. He tells me that he found it hard to detach himself from his ex-girlfriend and that his wife was also very friendly with a male colleague of hers.
"I have no doubt that we were in love with one another but we were also in love with other people and another way of life. I've only realised now that we might have been able to make it work if we had just abandoned the belief that what we were doing was wrong."
He goes on to tell me that although he and his wife were happy together they both had sexual affairs with other people. They split up when the dishonesty became unbearable. Now he tells me that he and his wife have agreed that maybe, if they had discussed having an "open relationship" things could have worked out.
"Who knows," he says, "one day we might be ready for that, right now it's painful because we hid so much from one another."
Many believe that Sienna Miller has made a significant point about modern-day relationships and agree that when it all boils down we are indeed "nothing but animals".
I asked a group of women to tell me what they thought of the concept of monogamy.
One single 27-year-old emailed me: "Monogamy is an event where two people are co-incidentally bored with others."
Another divorced woman with children wrote: "Monogamy is another word for jealousy and possessiveness."
One engaged 30-year-old wrote: "Monogamy is a convenient construct of the civilised world."
And a single 28-year-old wrote: "Monogamy is the endless impossible they taught us about in religion class, I know nobody in a truly monogamous relationship, it's a fantasy dreamt up by fantasists."
Whilst there were some positive comments, an overwhelming majority of women saw monogamy as an ancient monolith of a bygone era. Words used to describe it included "unreal", "impossible", "old-fashioned catholic ideology", "over-romanticised and under-exercised", and "near-impossible".
Annie is 30 and lives with her boyfriend of four years, they have an open relationship with rules.
"We don't feel that we need to conform to anybody's ideas of where the boundaries for our relationship should be," she says. She and her boyfriend say they are allowed to be with other people and are open with one another about this. They also encourage one another to form emotional as well as sexual bonds with other people.
"We don't even need to discuss this or explain to one another, we know the boundaries of our own relationship, for instance if we are walking around town and I see a nice-looking man I might say 'God, he's gorgeous' and that won't cause insecurity, in fact it makes things better, we're open about what goes on in our minds."
Annie's parents split up when she was 17. Her father was having an affair with his secretary since Annie was 13.
"I was devastated, not because they split up but because my mother knew he was having an affair for four years and was pretending it wasn't happening. I think she wanted to stay together for my brother and I, but they just didn't communicate, they didn't try to understand and the separation was angry and bitter when it finally happened."
Asked if she thinks her open relationship arrangement is a reaction to her painful childhood she says: "I know that everybody likes to think they are in the perfect relationship and at times things can seem perfect, but we all have vulnerabilities, sooner or later we give in in some way, I suppose I'm a realist."
She goes on to tell me that a male friend of hers in a monogamous relationship with his wife for eight years has recently gotten a 25-year-old girl pregnant.
"No one will believe that this has happened because he and his wife are so happy and dedicated to one another, if ever there's a case for having an open relationship that's it, I mean how could he make love to his wife with that secret," says Annie.
Nobody I spoke to claimed to have the perfect relationship and many said they had forgiven what they once thought was unforgivable.
Andrew forgave his girlfriend when he discovered that she had slept with a mutual friend, "They had a fling, it was the worst thing that ever happened me but I couldn't cast the first stone because I have done things like that in previous relationships, I do believe you can still be in love with someone and do these things."
At a Pepe Jeans party with Jude Law in London last week Sienna Miller said: "The only thing I know is that Jude is my dear friend. I care about him. Our relationship has been through very difficult times and there's something inside me I don't like about it now. There are things that will never be the same."
Those who have completely turned their backs on monogamy may well find themselves discovering the World Polyamory Association which is seeing its membership increase year on year. They describe polyamory as a philosophy of being involved with multiple, long-term intimate partners. They distance themselves from 'swingers' and emphasise that polyamory is not about sexual promiscuity but about creating emotional and sometimes sexual bonds in an open and respectful manner.
Such is the new nature of this type of relationship that an entire lexicon has evolved around it. Would-be 'polys' are encouraged to investigate the possibilities of having a lifestyle with more than one lover. Enthusiasts discover how to 'uplevel' jealousy into 'compersion' (joy at your lover's joy) and can look forward to feeling 'frubble' - this is the feeling of warmth and happiness a poly can feel when they see their loved ones with another lover.
One polyamorist described how comfortable she and her partner have become with their lifestyle, "sometimes we'll go for months when it's just the two of us. But if I just happen to be busy or not in the mood, then I'm not going to stop him. For example the other night I had lots of work to do, so when Simon brought a new girl home, I was in the bedroom while they took a bath, later I walked by and just said 'hi'."
She warns that as polyamory becomes increasingly popular and more widely accepted people should give serious consideration before jumping into such a relationship.
"If you can't manage one relationship healthily, you are not going to be able to manage two or more, relationships are like a consuming hobby, they take up a tremendous amount of time."
Polyamory is not free from jealousy but it focuses on acknowledging such feelings and discussing them. A "wibble" describes the temporary feeling of insecurity when seeing a partner being loving or close with others. Wibbles can turn into frubbles when you observe a partners 'NRE' - short for 'new relationship energy', a phrase describing how one partner behaves when starting a new relationship with a new lover.
"I'm a private poly, a closet poly," jokes a friend of mine when I tell her about polyamory, "I love the idea of finding someone that would be strong enough to give that type of relationship a go, it's honest and real, all my relationships have failed because of insecurities, I know loads of frustrated private polys. They act like this anyway so they may as well find someone to be open about it with, I call them 'male sluts' or 'man-whores'."
Popular polyamorist reading is a 1997 book called The Ethical Slut by Dossie Easton and Catherine A Liszt.
The book describes living with and loving multiple partners and encourages women to reclaim the word 'slut' as a positive term to describe the possibility of having simultaneous relationships with a number of people. Since its publication, internet chat rooms, forums and mailing lists have sprung up across the world focusing on polyamory.
Dr Meg Barker, a senior lecturer in psychology at London South Bank University and a practicing polyamorist, emphasised that it is about "the recognition of multiple important relationships" and she dispelled accusations that multiple partners meant a lack of commitment.
"Some people assume I am more open to offers, some polyamorous people do have a lot of casual sex, but for me it is about having loving relationships with a number of people at the same time."
While the term 'slut' has been reclaimed as an empowering and even endearing term that can now be applied to both male and female, the term monogamy is a remnant of times gone by for all too many. In a society where we are expected to have the perfect home, the perfect car and the perfect children it's no surprise that we also feel the need to have the perfect relationship.
For Sienna Miller as for many others it takes a hard fall to realise that no relationship is perfect. Call it monogamy or polyamory, both are feeble attempts at imposing order on the spontaneity and unruliness of overwhelming human emotions.
* Not his real name. All names have been changed