Her second round of celebrations comes after she declared her love for the athlete in a separate Instagram tribute. Sharing a photo of the pair cuddling up to each other, Lauren captioned the snap: "Happy Birthday JB, I love you."
As we know, this is the first time she's publicly declared her love for the dad-of-two, who announced his split from his fashion blogger wife, Nadia Bartel, in August.
While they've been avoiding the spotlight in recent weeks— dodging the prying eyes of the public to enjoy a holiday in Yarrawonga, Victoria— Lauren and Jimmy can't escape rumours they've been dating for some time now. More fuel was added to the fire when an old photo of Lauren's emerged with a caption that suggested she was secretly seeing him while he was still married.
Three months ago, while Lauren was living in London and Jimmy was travelling around the UK, she said she was "undecided but in love". While the post may seem irrelevant, knowing she'd had relocated to the UK when Jimmy visited the British capital adds more weight to Nadia's previous comments about his holiday.
"I don't want to comment specifically on what's been reported about Jim's trip to the UK as I don't think it's in anyone's interest," Nadia told the Herald Sun, all but confirming she knew he'd spent time with Lauren while travelling abroad.
Despite the fact Lauren is yet to address speculation they've been together for some time now, her friends have been rallying around her amid the intensifying drama, flocking to social media to praise her for finally going public with her romance.
"So happy for you, my darling Loz," one pal wrote underneath a photo of the couple. "Good to see you guys happy and enjoying life."
Another wrote: "Really happy for you, love that you kept it classy."
Not surprisingly, many took exception to the glowing comments, however, her pals were there to defend her: "Why can't we be happy for two people who clearly found genuine love and support in each other? She makes him look really happy. No one will know how long ago the love left that last relationship," she said, referring to Jimmy and Nadia's marriage.
"Don't be bitter. It's not always the man's fault, wives push men away all the time."
Another one of Lauren's loyal followers weighed in, taking the opportunity to blast Nadia, despite the fact the person defending her had already deleted her comment.
"And a vacuous, self-absorbed, selfish wife too, Jimmy deserves to be loved and adored. Nadia will be fine, she loves and adores herself."
Jimmy announced his split from his wife— who he married at the Bellarine Peninsula in 2014— on August 15. Speaking about the breakdown of their marriage in September, he admitted their current situation "is not great".
"I am probably not going to provide any commentary on it," he said. "I know I am in the public eye and people are interested, but it is a private matter and I ask for a bit of respect because obviously Nadia and the boys [are] involved.
"I know I am in the public eye and people are interested, but it is a private matter and I ask for a bit of respect because obviously Nadia and the boys [are] involved."
Nadia has since moved out of their home and into her parents' house. According to The Sunday Telegraph, the mother-of-two will not be changing her name back to Nadia Coppolino in the wake of their separation