Warren Buffett's two wives: 'It worked well but it wouldn't work for a lot of other people necessarily'

Warren Buffett is one of the most famous billionaires in the world, having built his fortune as a trader to become the second-wealthiest man in the US.

What is little known about Buffett, 86, is that he had two wives, both of whom knew about each other and both of whom he credits with shaping him into the incredible man he became.

His complicated personal life is exposed in recent HBO documentary Becoming Warren Buffett.

Warren Buffett and his first wife Susie on their wedding day in 1952. Image: HBO

It's a long story.

Buffett and Susan fell madly in love and married in 1952 when he was 21 and she was 19. 

"There were two turning points in my life," the billionaire said in the documentary. "Once when I came out of the womb and one when I met Susie, basically."

"She was the girl, yep, but it took her a little longer to figure out I was the boy."

Those first few years were blissfully happy for the pair, with the couple settling in Omaha in Nebraska.

The future-billionaire had finished business school and was just beginning to build what would become his empire and Susan stayed at home with their three children, Susie, Howard and Peter, now aged 63, 62 and 59 respectively.

Warren and Susan Buffett with children Susie, Howard and Peter. Image: HBO

Susan was happy in her marriage but described her husband as complex and a loner.

"I think sometimes geniuses are sometimes by default lonely and isolated," Susan said during her last recorded interview. "We were like parallel lines.

"Very connected when he was open to connecting."

Buffett and Susan were married for 52-years. Image: HBO

However as her children became older, the mother-of-three dreamed of having her own life and left her family to move to San Francisco, leaving them devastated.

In Susan's mind, she wasn't leaving the marriage or her children, it was just her turn, and eventually, they came to understand and accept her decision.

"I said, 'I'm not leaving you, because I'll be wherever you want me when you want me,'" Susan said.

Buffett and Susan at an event shortly before she began her battle with oral cancer. Image: HBO

Their daughter Susie was concerned because she said her father couldn't function without her mother.

"It was devastating for him," she said. "I came home because - I can't say I was mad at her exactly but - I kept thinking, 'How can you leave him? He can't function by himself.'"

Not wanting to leave her husband to fend for himself, Susan asked her close female friends to look in on him when they could and eventually one friend, Astrid Menks took on the role.

Buffett with companion and then second wife Astrid. Image: HBO

She eventually moved in with the businessman, with Susan's blessing.

"I don't go to most things in Omaha because I figure Astrid lives there with him and that's for her to do," she said before her death in 2004 from oral cancer at the age of 72. 

Buffett and Susan ended up spending half of their 52-year marriage living apart.

Susan and Astrid were best friends who "loved each other". Image: HBO

Daughter Susie said in the documentary, "Strange as it may seem to people I always think, you know, who cares? If it's working between the people who are directly involved, who cares what anyone thinks."

"And my mother and Astrid were very close," she said. "They really, really loved each other and I think that my mother was glad that she was there, you know, she loved my dad. She wanted him taken care of and happy and there's no one better than Astrid.

"I mean, she [Astrid] loves my dad, wouldn't care if he didn't have one cent."

Astrid became Buffett's official second wife in 2006. "Well, Astrid has lived with me for a long time. She's done wonders for me," Buffett said in Becoming Warren Buffett. "It worked well but it wouldn't work for a lot of other people necessarily.

"Susie and I loved each other, we admire each other, we were totally in sync with what the other was doing, but we were two different individuals."