The Enquirer recently cited an unnamed "Oval Office insider" who claimed the couple "are now sleeping in separate White House bedrooms".
The White House has said that Michelle's solo break was something of a present from Obama.
"As part of her birthday gift from the President, the First Lady will remain in Hawaii to spend time with friends ahead of her upcoming 50th birthday," a brief White House statement said.
White House press secretary Jay Carney added: "If you have kids, you know that telling your spouse that they can go spend a week away from home is actually a big present."
The buzz began after a picture from Nelson Mandela's memorial service in December showed a glum looking Michelle looking the other way, as her husband and British Prime Minister David Cameron posed with Danish Prime Minister Helle Thorning-Schmidt.
Obama has previously acknowledged that his marriage has had ups and downs as they coped with the pressures of dual careers and the arrival of their two daughters, Sasha and Malia.
