Nicole snubs Keith on the red carpet

He claimed she had the flu, but friends say Keith was riding solo after a bitter fight with HIs wife

When Keith Urban arrived at the Grammys last week, awaiting fans and media were shocked to see he was on his own – with his wife Nicole Kidman nowhere to be seen.

And you can’t blame them – it’s rare to see him at music events without Nicole nuzzled into his side, providing photographers with countless public displays of affection.

But this time, Keith, 52, who was there to present an award, looked “out of place” without Nic, also 52, and seemed uncomfortable answering questions about her whereabouts.

“My wife is home with the flu,” he muttered to a reporter. “A lot of that going around.”

But once inside among the rest of the A-list stars, a witness says Keith let his guard down and told friends what was really going on.

“He seemed incredibly sad and distracted,” says one onlooker backstage at Los Angeles’ Staples Center. “It was clear something deeper was going on. He looked visibly distressed – kind of like a defeated man.”

Adds another, “He fit in with the sombre mood as everyone had just found out Kobe Bryant had died, but it was clear something else was going on with Keith.”

A source close to Keith’s long-time buddy, fellow country singer Blake Shelton, who was also backstage, reveals Nicole was a no-show following a fight between the couple just hours earlier.

“He told Blake how him and Nicole had a furious argument that morning over his decision to extend his Las Vegas residency,” claims the confidante. “Nicole ended up storming out of the house with their girls in tow.”

Nic and Keith are widely reported to have struggled throughout their 13-year marriage over their clashing careers, and once tried to enforce a rule that they’re never apart for two weeks.

According to sources, this rule has slipped by the wayside as their daughters Sunday, 11, and Faith, nine, get older.

Our Blake source reveals, “He said Nicole begged him not to add any more dates and was fuming when he went against her wishes. She accused him of constantly trying to find excuses to be apart from her.”

Despite usually being the calmer partner, Kiwiborn Keith retaliated. “Her comments sent him into an uncharacteristic rage,” says the source. “He told her he was sick of constantly taking a back seat to his career.”

Indeed, whenever Nicole

is promoting her work on a red carpet, Keith moves heaven and earth – or at least a private jet – to ensure he can be supportively by her side.

Says a source, “He’s starting to realise that Nic isn’t as keen to pay back the favour. Regardless, he hates fighting and was a total mess by the time he was due on stage. He seemed extremely stressed and kept frantically checking his phone throughout the ceremony.

“It looked like he was trying Nicole just minutes before going on stage to present, but there was no answer. He had to be calmed down by one of the producers as he admitted he was having some ‘personal problems at home’.

“Keith left as soon as the ceremony ended.”