Australia's Princess of Pop and the country's inaugural Australian Idol winner... it was the romance that had the country excited.
But 16 years later, Delta Goodrem and Guy Sebastian's 2003 lovefest is said to still be causing quite the strain between the new Voice coach and his stylist wife, Jules Sebastian, 37.
A source reveals that the mother-of-two is none too happy with Guy for fuelling chatter about his loved-up encounters with the 34-year-old songstress.
"She's annoyed about it constantly being brought up," reveals the source. "Frankly put, it's a story no wife wants to repeatedly hear about, especially now they have two kids.
"Jules knows this is all part of the business, but that doesn't mean she's not bothered by it."
Prior to this season's premiere, Delta and Guy, 37, spent countless press opportunities and even time on the show speaking about their brief romance.
"She was so sweet and we just hit it off straight away and became really good mates," Guy revealed. "She romantically chased me for a very long time. After repeated rejection, I caved in finally for just a little while. Is that the story she tells?"
WATCH BELOW: Guy Sebastian and Delta Goodrem spill all on their secret romance during a revealing segment on The Voice. Story continues after video...
In 2015, Guy confirmed on The Kyle and Jackie O show that The Voice co-stars-to-be had been on "a few dates" – igniting cheating allegations, considering he was married to Jules at the time.
And while he later clarified that he and Jules were on a break when he wooed Delta, it's surely a time in Jules' life that she would rather forget about.
The source explains that it's taken a lot for Jules to be supportive of Guy working so closely with Delta, who he has described as "gorgeous" and his "hall pass".
"Delta's loved up with Matthew [Copley] so there's no chance of her and Guy being more than friends, but the fans just love anything to do with Guy and Delta so it's inevitable that they'll keep getting asked about it," says the insider.