For any mother, seeing their teenage daughter forming a close bond with their dad's much-younger new wife is heartbreaking.
But for Cassandra Thorburn, watching her daughter Ava, 14 – who now goes by her middle name Willow – looking glamorous in a two-piece suit sitting front row at the Australian Open with her dad Karl Stefanovic, 45, and her new stepmum Jasmine is particularly tough, given Jasmine is the woman Karl moved on with shortly after walking out on his family in 2016.
"Cass hates the thought Ava will be exposed to stuff that's beyond her years, and the fact Jasmine and Ava have obviously gone shopping together is upsetting," a close family friend tells.
"Cass knows Ava is impressionable and would have loved it, but in her mind she looked more like a 25-year-old than a 14-year-old and she doesn't want her growing up too fast.
"Of course she struggles with the fact that Jasmine is part of Ava's life – she'd have to be a saint not to find it hard that the woman her husband hooked up with after walking out on her is now buying expensive clothes for her daughter.
"That said, Cass accepts that it's a part of their 'new normal' and she knows while Jasmine might be the good-time, cool stepmum, inviting Ava to fun events and taking her shopping for glamorous outfits, she's the one who does all the important stuff, like getting things prepared for the new school year, making her home life happy, taking care of what she eats and making sure she's safe."
Further fuelling 48-year-old Cass' irritation is the fact Ava is getting a strong taste for designer clothes, and she places the blame firmly at 35-year-old Jasmine's feet.
"The way Cass sees it is Ava was happy being a kid wearing Doc Martens and jeans, but since Jasmine came along she's buying her Zimmermann dresses and taking her to parties with an older crowd. She's fed up with Karl and Jasmine letting Ava do whatever she wants, while she's left picking up the pieces and being the disciplinarian."
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The final straw, says the friend, was when Cass found out shoe designer Jasmine had even named a pair of suede stiletto boots after Ava.
"More than anything, Cass hopes Jasmine is a good role model to Ava and she isn't just practising being mum on her daughter."