The pair first met in LA, where US-born Brynne was working as a fitness instructor.
They tied the knot in a $3.3 million ceremony at Melbourne’s Crown Casino. Geoffrey was 66, while Brynne was just 26.
In 2012, Channel Seven gave the couple their own reality show, Brynne: My Bedazzled Life.
“Once I sent him an invoice for over $200,000 worth of new clothes. I honestly thought he was going to kill me,” she recalls. “But he didn’t care."
She added: “Publicly, Geoffrey was very flashy, but he was very reserved at home.”
Brynne has no issue confirming that she and Geoffrey never slept together.
“It wasn’t my decision. It was something we never really talked about," she said.
"In the beginning, I assumed we were waiting for marriage, but then it didn’t happen. I thought maybe it was all the medication he was on … then after so long you kind of forget about it.
“It was confusing to me, because in a marriage that’s what you do. To this day, I don’t really understand it.”
While Brynne was labelled a “gold digger", she maintained she never married the eccentric millionaire for his money.
“Money is nice. Nobody is going to turn money down. But it was never about that. Believe it or not, Geoff can be very, very nice,” she told Stellar.
In January 2014, it was announced Geoffrey and Brynne’s four-year marriage was over. Brynne insists she doesn’t regret the split, but doubles down on her decision to keep her famous surname.
“I don’t associate my name as an attachment to him – it’s just my name. I don’t see any reason why I would change it – that’s my identity with or without him," she said.
“I have no regrets from that time in my life. Not at all. With all the good times and bad times, that’s what’s brought me to where I am today. Everyone goes through hard times, but I’ve had a lot of amazing times, too, that I wouldn’t trade for anything.”
One year after Brynne and Geoffrey separated, he wed his third wife, model Gabi Grecko. She was 46 years his junior.
The pair split after only a few months. Brynne says the fallout led Geoffrey back to her – with the exes reuniting for the very last time in 2015.
“When [Geoff and Gabi] broke up, we had lunch. He was telling me about how things ended and he was quite upset about it,” Brynne reveals. “Gabi and I have never spoken – she was not a fan of me from day one. I never really understood why.”
After a short-lived engagement to comedian Brett Hunter, Brynne finally found her happily ever after with new boyfriend, Brok Eastwood, with whom she went public in March this year.
"We’ve known each other since at least 2014 through people, but we didn’t know each other personally until recently. He messaged me on Facebook a few times and I was reluctant at first, but I thought, what do I have to lose?" she told New Idea.
"So a week before my birthday [in January] we had our first date and it was amazing. I have literally not gone home to my apartment since!"
Brynne said her marriage to Geoffrey made her "hold back" when heading into new relationships.
"I don’t want to get hurt and I don’t want to jump into something … but never say never because then you jinx yourself."
And as for having her own family one day, Brynne says she’s leaving it up to the universe.
“That is something I have always wanted, but after realising that it may not be possible for me, I just have to accept that and that’s OK. It’s not that I can’t have kids ... I don’t know if I could do it without IVF or if I could do it at all, even.
“So it’s one of those things that I’ve just had to accept and go, ‘You know what, it may not be on the cards for me.’ Of course, [though], I would love it more than anything.”
Before Geoffrey met Brynne, in 1984, he married former-model-turned-nurse Leanne Nesbitt, who was just 20 years old at the time while he was 41.
In 1988, the pair got divorced and Geoffrey filed for bankruptcy and deregistered as a medical practitioner.
Geoffrey later claimed Leanne received $3 million from their divorce and said he hadn't spoken to her in years, rubbishing her claims that he would seek relationship advice from her.
"I don't call her asking for marital advice. Why would I do that when our marriage collapsed? What nonsense. It's just a pack of lies. I haven't spoken to Leanne in years," he told the Daily Mail.