Where is Melania Trump? It's the whisper in Washington, DC, that is growing louder and the controversial question that has White House watchers wondering. The first lady of the United States is missing in action.

Apart from a handful of appearances, the wife of the 45th and 47th President Donald Trump has been notably absent from the East Wing since her husband was inaugurated earlier this year.

For author Michael Wolff, who has spent the past decade chronicling the president, the answer is simple, the first couple are "not together".

"At one point I asked someone who's very close to them, and I said, 'so what's going on?'" he told 60 Minutes. "And this person looked at me like I was a real dunce and then said, 'she hates his f---ing guts'."

It's an allegation hotly disputed not only by the White House but also Anita McBride, an expert on American first ladies and their legacies. "I think it's a marriage that works for them," McBride told Dimity Clancey. "Maybe it's not your definition of a happy marriage, maybe it might not be mine, but it's certainly theirs. I think that's a lot of wasted words. I really do."

One of the most contentious issues is the decision by Mrs Trump to not live in the White House with her husband full-time.

"I will be in the White House. And when I need to be in New York, I will be in New York. When I need to be in Palm Beach, I will be in Palm Beach. But my first priority is to be a mum, to be a first lady, to be a wife," she said in an interview with a US broadcaster late last year.

But Wolff said there are other instances where Mrs Trump's absence is telling, such as her decision to not accompany her husband to court or on last year's campaign trail. "It's glaring, it's exceptional. It's never before been played this way. And it is played in such an obvious way that I think one would be remiss in not taking the obvious message … These are two people who live separate lives. Everything is separate. They are not together," he said.

The Trumps first met nearly 30 years ago in a New York club.

Kate Bennett, who wrote a book about Mrs Trump in her first term as the country's first lady, said back then the former model from Slovenia was drawn to the brash billionaire's "magnetism, his celebrity, his wealth, his connections". But she says scandals such as the allegations by porn star Stormy Daniels that her husband had been unfaithful were "crippling" for Mrs Trump.

"I mean, two things can be true. She knew who she married. She wasn't marrying a saint," Bennett said. "She knows the guy is not known for his monogamy, right? Did she think that their private marital issues would be so publicly divulged. Absolutely not."

Wolff agrees the incident is behind Melania's alleged disdain for her husband. "He has a long history of relationships with other women, porn stars and the like, and that he's not a very nice guy, and he doesn't listen to anyone ever," he said. "So I doubt if he would listen to his wife. Should I go on?"

Whatever the reality is of the first couple's relationship, the issue is clearly a sensitive one for the White House.

60 Minutes approached the office of the first lady for a comment but rather than respond to specific questions it hit back with a blistering statement. "It is unprofessional and irresponsible for 60 Minutes Australia to tarnish and defame the reputation of the First Lady of the United States," it said. "The details of Mrs Trump's personal life and family should be respected as private. One must consider the potential harm caused by creating unfounded narratives solely to garner clicks."

For Wolff, the mystery of Mrs Trump's whereabouts remains a legitimate question. "During the first White House, she wasn't there. During this White House, she's not there," he said. "This is a significant question in American politics: where is Melania?"

Watch the full episode of 60 Minutes on 9Now.

Source: 9Now.