Tara Brown was alledgedly seeing another man in the months before her abusive former boyfriend beat her to death, according to an anonymous source.
The pair reportedly met at a game of touch football back in May 2015, four months before Lionel Patea ran her off the road and bludgeoned her to death, the Daily Mail reported.
The other man, who has not been identified, allegedly has a partner and children.
He only met Brown once in public for a walk along a beach during their affair, the 29-year-old told police.
Otherwise they were careful only to meet as part of a larger group, according to the Gold Coast Bulletin.
The man revealed their relationship had become "intimate" before 24-year-old Brown was killed, though did not go into details or give an exact timeline.
They texted each other around 10 times a day, he said, and sometimes spoke on the phone but only when it was "safe to do so".
Only a few close friends knew of the relationship, he claimed, adding: "Tara and I would joke around that one day if we were both single, you know, things could be different and we could have a real relationship."
Patea reportedly became aware that something was going on during a trip to New Zealand to scatter her grandfather's ashes.
After discovering a text on Brown's phone, Patea allegedly pulled her up a flight of stairs by her arm and had a confrontation before Auckland Airport security had to separate them.
After returning from the trip, Brown stopped contacting the other man, telling friends not to reply to text messages because Patea had her phone.
It has since emerged that Patea spent that final week threatening Brown, cornering her in her Gold Coast home and holding a pair of scissors to her throat.
For two days after the attack Patea kept her from seeing her daughter. She eventually asked her boss for help, and he took her to the police to apply for a temporary protection order.
She also contacted a women's refuge in her attempts to escape from the abuse, the Courier Mail reports.
Brown got in contact with the other man again shortly before she was killed, after getting a new number.
They had been due to meet on September 8, the day Patea rammed her car off the road before beating her to death.
The man said he visited Brown in hospital after the attack, and sat in her room for around 45 minutes.
Patea, 25, a former Banditos bikie, pleaded guilty to killing Ms Brown on what was expected to be the first day of a weeks-long trial into her murder last week.
In a statement read outside court, Patea said he changed his plea because "I do not wish to cause Tara's family any further pain nor delay their need for justice."
He was later sentenced to life behind bars.
Two police officers have since been disciplined for failing to grant a domestic violence protection order, despite Brown's pleas.
Brown's application was rejected despite the fact Patea was "known for his violent behaviour" and had "a record as long as our arms", according to a police investigation that was published by the Brisbane Times.
Brown's mother Natalie Hinton criticised the police for the way they handled her daughter's case.
"Because Tara went a few days after the events leading up to us visiting the police station, they queried her on why she didn't come straight away," she told Today.
Brown was issued with a protection order days later, but it did nothing to prevent her murder.