Billionaire tech entrepreneur Elon Musk has been referred to as the Thomas Edison of the modern moment.

The South African born 46-year-old has revolutionised the electric car, was instrumental in the creation of PayPal and is now making some of the greatest innovations in space travel the world has ever seen.

“He does what he wants, and he is relentless about it,” Elon Musk’s first wife, Justine Musk, once said. And it is unequivocally this quality that has made him the best on the planet at what he does.

But it also – according to his ex-wives – makes him a very particular kind of husband.

“It’s Elon’s world,” Justine continued, “and the rest of us just live in it.”

Justine Wilson – now an author – and Elon Musk met at Queen’s University in Ontario. In an interview with Marie Claire, Justine recalled Musk lending her his credit card to buy as many books as she wanted.

In 2000, the two married, and Justine recalls an unusual conversation they had on the day of their wedding.

As they danced at their reception, Musk said to her, “I am the alpha in this relationship,” and though it was an unusual thing to say, Justine implicitly trusted him.

A few months later, she also trusted him when he presented her with a postnuptial agreement, one that would serve Musk very well in the future.

“I shrugged it off,” Justine wrote in Marie Claire in 2010. “But as time went on, I learned that he was serious.

“He had grown up in the male-dominated culture of South Africa, and the will to compete and dominate that made him so successful in business did not magically turn off when he came home.”

Often, she would find herself snapping at Musk, “I am your wife, not your employee.”

He would swiftly respond, “If you were my employee, I would fire you.”

Musk, according to both his ex-wives, has always been unsurprisingly addicted to his work. When he was not physically at work, Justine recalls, that's where his mind was.

This certainly was not the marriage she had hoped for - and in 2008, her husband who she had imagined growing old with, the father of her five sons, filed for divorce.

Six weeks later, she received a text message from him. He informed her that he had fallen in love with British actress Talulah Riley, who at the time was in her early 20s, and the two were engaged.

Quickly, Justine discovered that with her postnuptial agreement, she had effectively signed away her rights as a spouse, and had no claim to any shared property other than their house.

She reflected in 2010 that the social world she had lived in as the wife of Elon Musk had been an oppressive one.

LISTEN: The importance of space travel. Post continues below.

"The females who populated it were the young wives or girlfriends of wealthy men, or the personal assistants who catered to them.

"Women disappeared after some point in their 30s, and any female ambition other than looking beautiful, shopping, and overseeing the domestic realm became an inconvenience."

She felt that ultimately, the ambition that once drew Musk to her, was what, years later, pushed him away.

In 2010, Musk married Talulah Riley. She once said of her relationship with him, "I remember him saying, 'Being with me was choosing the hard path'.

"I didn't quite understand at the time, but I do now. It's quite hard, quite the crazy ride."

One year later, the pair separated, and in January 2012, Musk tweeted, "It was an amazing four years. I will love you forever. You will make someone very happy one day."

They then officially divorced, before marrying for the second time in July 2013. In 2015, they filed for divorce (again), before withdrawing a few months later.

In 2016, they divorced, and Musk told Forbes, "We took some time apart for several months to see if absence makes the heart grow fonder, and unfortunately it did not. I still love her, but I'm not in love with her... I can't really give her what she wants."

Musk has since dated actress and ex-girlfriend of Johnny Depp, Amber Heard, but their relationship ended in November of 2017.

He told Rolling Stone last year, "If I'm not in love... I cannot be happy.

"I will never be happy without having someone. Going to sleep alone kills me.

"It's not like I don't know what that feels like... being in a big empty house, and the footsteps echoing through the hallway.

"How do you make yourself happy in a situation like that?"

But it seems maintaining a relationship, and pioneering technology that promises to change the world, are two things that are rather difficult to do at once.

Listen to the full episode of Mamamia Out Loud, here.