I’m surprised that they’ve lasted as long as they have, quite frankly. She seems like someone who would be difficult to live with.
As she fast approaches her 49th birthday, friends say the superstar is suffering something of a "sense of humour failure" about her appearance.
Worse still, relations with her husband are "more strained than ever".
"It’s awful. She looks like an ageing transvestite and Guy looks like a cross between a football hooligan and a pervert," says one source close to the couple.
"Worst of all it portrays Guy as a clinging subservient type and Madonna as the alpha female. Guy’s hyper-sensitive that everybody thinks that about him - his mates wind him up by calling him ‘Mr M’ - and he will not see the funny side."
Yet while the image of Madonna undeniably does a huge disservice to a woman in phenomenal shape for her age, friends have waspishly commented that Guy is looking more like his cartoon every day.
A karate enthusiast, the film director has grown noticeably more musclebound in the past year, while his freshly shaven head has lent an unkind hardness to his appearance.
Worryingly, friends say Madonna is "not a huge fan" of his individual take on football hooligan chic.
"This seeming image gulf between the two is reflected in the way they have started to lead quite separate lives with Guy doing his thing and Madonna hers," the source says.
"He has a very close band of his friends and she has a tight group of her own.
"She likes to be in the house or out to dinner with a few chosen couples but Guy wants to be at his karate classes, in the pub or hanging out with his mates."
Amid all this, friends say Madonna has hit on the notion of moving - lock, stock and two (smoking) barrels - back to New York, the city she’s always called her home.
"This is a massive step she’s taking and she knows it. It’s absolutely critical to her and Guy’s future. That’s all she cares about."
This drastic course of action, revealed by the Mail in January, comes at a time when Madonna’s confidence has hit a new low.
Over the past few months the singer has already suffered a number of knocks, leading her to joke grimly with friends that she is suffering her own ‘annus horribilis’.
First there was the fallout from her decision to adopt the Malawian baby David Banda. Madonna has been left deeply wounded by what she perceives as the public’s hostility to her decision.
Far more damaging, however, is the looming threat of a tell-all book by former nanny Melissa Dumas.
Provisionally titled Live to Tell, after one of Madonna’s early hits, someone who has seen the synopsis describes it as, a ‘laundry list’ of allegations of savage rows behind closed doors between Guy and Madonna, their children’s behaviour, the family’s participation in Kabbalah and the controversial adoption of baby David (or Davey, as Madonna calls him).
Hence, as confirmed by Guy’s father, John Ritchie, the mooted move to the USA.
"They are moving to New York," he admits. "They have been looking for somewhere to live for a bit. I think Madonna just wants to be there. And the children can all go to the bi-lingual French Lycee school (Madonna is insistent that her offspring are educated in French), so it will work for them."
Guy, however, is understood to be not quite so enamoured with the notion of crossing the Atlantic.
He was not present when she viewed a series of grandiose New York town houses recently, with her favourite being a £20million, 14,700-square-foot mansion on East 62nd Street.
The 103-year-old, six-story Beaux Arts-style mansion has seven bedrooms, 10 bathrooms, three kitchens, nanny and servants’ quarters, gymnasium and sauna.
Certainly the couple have not been seen out in public nearly as much as they used to be. They have only been spotted twice in public since February - once at dinner with fellow American Gwyneth Paltrow at Cecconi’s restaurant on March 28th and then at a pre Oscar Vanity Fair party at Mortons in Hollywood in February.
"They aren’t spending a lot of time together at the moment," says a source close to the couple. The truth is that they seem to have less and less in common.
"When they met, both of them embraced the other’s interests with a passion. Back then, Guy was one of the hottest film directors around and Madonna was thrilled to marry him and dreamed of becoming his muse and appearing time and time again in his films.
"She’d talk about Guy non stop to her girlfriends with real passion in her eyes. But that’s not the case these days."
Likewise, Guy’s passion has cooled: "To be honest, Guy was star-struck when he first started dating Madonna," says one of his drinking friends.
"He couldn’t believe this huge star was interested in him and was never a real ladies man so he was completely bowled over.
"Now Guy fears deep down that he’ll be forever Mr Madonna and it’s true to say, his career hasn’t exactly blossomed since she came on the scene."
Indeed, while Madonna continues to find success with nearly every project she pursues, Guy, who was once such a hot director he had Brad Pitt begging for a role in one of his films, has been reduced to working on rather smaller projects, such as a television series called Suspect with a cast of relative unknowns.
Friends also suggest Guy has effectively turned his back on Kabbalah - the Jewish cult his wife has so enthusiastically embraced - and is far more likely to be seen nursing a pint at his local on a Friday.
In stark contrast to the Howson painting, Madonna is, in fact, looking better than ever.
Along with regular Harley Street ‘beauty treatments’, the 49 year-old mother of three has been having treatments to dye her roots.
But even she cannot stop the march of time and friends say the adoption of Davey came after Madonna was finally forced to face the fact that nature had taken its course and she is now too old to conceive naturally.
"Doctors told her that it wasn’t medically safe for her to have a baby a few years ago," says a source.
Nevertheless, she exercises enthusiastically to keep her body as young and supple as is possible, with four-hour workouts seven days a week.
"She’ll be doing her workouts on a daily basis well into her seventies," laughs a friend. So what next for the most successful singer of her generation? There is talk of another album and developing her new career as a clothing designer (she has just launched her first range through H&M, though it must be said to a lukewarm response).
Another children’s book dedicated to Davey and rumours of a cameo acting role in the hit US television series Nip/Tuck are also mooted.
Overshadowing all of this, however, is her former nanny’s £3million book deal. So far a team of lawyers have managed to hold off its publication. But if and when, it is published, Madonna and Guy’s marriage will once more be exposed to the unforgiving eye of publicity.