Has Kate Moss and Jamie Hince's marriage hit the rocks over her obsession with spending more time with her girlfriends?

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At first glance, the sight of a leather-clad rocker chatting with a bubbly blonde in the backstage bar at the Glastonbury Festival last month was unremarkable.

Guitarist Jamie Hince is certainly not an uncommon feature on the celebrity circuit — not least because he is most famous not for his band, The Kills, but for being married to Kate Moss.

But onlookers couldn't help notice that the rail-thin, party-loving young lady so enjoying his company, with whom he seemed to spend much of the festival, was not his wife. It was, in fact, her rival - 28-year-old socialite Lady Mary Charteris.

Unconventional couple: Jamie Hince and Kate Moss wed in 2011 after enjoying a four year relationship

Nor were any of the numerous other women Hince, 46, was seen in deep conversation with that weekend in June - one of whom reportedly even pinched his bottom.

Yet this situation is now not uncommon. Indeed, it seems what has become far more normal for Moss and Hince these days, four years after they wed, is to find the two socialising apart.

Are the two living separate lives? Rumours are starting to fly. 'There have been arguments and jealousy although nothing is going on with either of them,' an unnamed source told a newspaper yesterday. 'There was a blazing row. Jamie has been saying he's worried he has wasted the last eight years.'

Their diaries do seem remarkably uncoordinated for a married couple. Last week, Moss flew in to London from a solo trip abroad, while Hince was pictured on July 2 leaving celebrity hangout The Chiltern Firehouse without her. Two days later, Moss was at the Miu Miu fashion show in Paris, again alone.

'Jamie is always saying that Kate is far more interested in spending time with her friends,' says a source. 'She was obsessed with Cara Delevingne and more recently, socialite Roxie Nafousi'

In fact, while Kate's party antics appear to have enjoyed a renaissance this year, the duo have rarely been seen out as a couple and were last pictured together in May.

And this month Hince will leave for a prolonged spell in America, where his band is touring until September. Kate is unlikely to join him as she famously does not get on with his bandmate, Alison Mosshart. No wonder, then, that the marriage is reportedly 'in crisis'.

Media reports have repeatedly claimed the romance is 'on the brink' and 'on its last legs'. Many in the fashion world, too, are now describing the union as 'all but over'. So just how have things seemingly gone so wrong so quickly?

One thing being blamed is the array of pretty blondes - not just around Hince but also Moss. Kate's groupies seem increasingly captivated by her risque antics. 'Jamie is always saying that Kate is far more interested in spending time with her friends,' says a source. 'She was obsessed with Cara Delevingne and more recently, socialite Roxie Nafousi. It seems Kate would rather be with the girls than her husband.'

One intimate of the couple tells me that a particular slump in their relationship came around February, with Jamie cheesed off with the way his other half was treating him while prioritising other people.

Kate was concentrating on building friendships, including with fellow model Cara - the chemistry between her and Kate is well displayed in recent campaigns for Mango and Burberry. The latter shows the pair embracing, apparently naked under their trench coats.

She is also in a racy new campaign for Balenciaga with Dutch supermodel Lara Stone - recently split from husband David Walliams. The adverts show the pair apparently seducing each other.

Close friends: Kate and her modelling protégé Cara Delevingne star in a Burberry ad together

Kate has previously expressed her admiration for Stone, saying: 'I think she's very hot, with her boobs and her teeth.'

Meanwhile Kate has been partying with renewed vigour, despite having celebrated her 41st birthday in January - highlighted by her being escorted off an easyJet flight last month for being disruptive.

'She's been off the leash and on the lash as the easyJet business shows,' the friend tells me. 'He just hangs about and walks the dog.'

He has also, it seems, been enjoying the company of other women - though his friendship with Lady Mary Charteris strikes some as particularly unfortunate given that she and Moss had a spat two years ago over mutual accusations of flirting with each other's husbands.

Jamie and Kate once had a very close bond, falling head over heels when they first met

Jamie and Mary were pictured sharing a ride on a golf cart, with her being described in one newspaper as a 'mystery blonde'.

Mary's Instagram account shows her 34-year-old rock star husband Robbie Furze was also at Glastonbury this year, and it was his initial close friendship with Moss that led to tensions between the two women reaching 'boiling point'.

But some might say these new friendships both are pursuing are a symptom rather than the cause of any marital strife.

After all, the romance has never been conventional. They first met not through friends or work - instead Kate was googling rock stars while on holiday in the South of France and came across a picture of Jamie online.

Sources say Kate and Jamie now barely see each other, as she works and parties while he tours

She told Vanity Fair: 'I went, 'Ooh I like the look of him.' A friend set us up. He turned up and we spent the next four days together.'

The two are certainly very different. While Moss is the Croydon schoolgirl turned eternally party-going supermodel who has carved out a £45 million fortune over 25 years, Jamie's background is impeccably middle class.

His father William was a pipeline construction manager and he grew up in the affluent village of Woolton Hill near Newbury, Berkshire. His immaculate blonde mother, Carole, favours nicely tied scarves and is a pillar of the community.

Neighbours remember him as a conscientious young boy who spent his time writing poems and short stories. He took A-levels and left Goldsmiths College in London with a first-class degree in drama. His punk sensibility seems to have developed after college.

Simon Williams, of Jamie's first record label Fierce Panda, says: 'Jamie was just a nice bloke, a very sweet little artistic person.'

Now it seems that conventional personality is clashing with Kate's free spirit. Yet he and Moss once had a very close bond, falling head over heels when they first met. Such was Hince's adoration that, in the early days, he had the words 'Kate uber alles' (Kate above all) tattooed on his arm.

Back then it was also reported that Kate stubbed a cigarette out on his hand when she caught him talking to another girl in a club.

Which is perhaps why Kate's friends insist Hince shouldn't now complain, as he knew what he was getting into.

'He worshipped Kate and doted on her from day one,' says one old friend. 'He knew marrying Kate was never going to be a conventional marriage - he was marrying Kate Moss for God's sake!

'Their power dynamic has always been that Jamie does what he's told and Kate does what she wants. Jamie has always had to play second fiddle to the fact that she had all the financial power and status in the relationship.'

The domesticity of marriage has also altered their lives dramatically. Since they wed in 2011, a homely lifestyle of sorts has prevailed. He moved into her £8.5 million house in Highgate, North London, and weekends were spent at her Cotswolds hideaway.

Both made no secret of hoping to have a child of their own - Kate has a 12-year-old daughter Lila, by ex-boyfriend Jefferson Hack. However, after a period of relatively clean living, she seems to have returned with a vengeance to her party lifestyle.

Kate has been busy professionally, too. It seems she has, in fact, been very busy doing an awful lot of things - except concentrating on her marriage.

Another friend of the couple told a newspaper on Sunday: 'Kate and Jamie have barely been seeing each other. Jamie has been saying he is sick of being about 'number ten' on Kate's priority list.

'Kate has apparently not been happy for some time and maybe that's why she's been partying a lot. They don't seem to have been making time for each other and, with Jamie often away in America, they've been living separate lives.'

Now it seems that separation may be taking a serious toll.