"Holly was one of the mean girls. No one talked to Holly, because the girls never got along with her in the mansion," the insider claimed to Daily Mail.
The source said all the contestants had a least one other girl they were close with, but Holly allegedly had "no one".
"She didn't make any effort to befriend any of the girls and gave the impression that she was better than everyone else," the insider said.
But Holly and criminal lawyer Carlie appeared to have become good friends during filming, and often post each other on their Instagram accounts.
However another insider refuted claims Holly was a mean girl, saying the 27-year-old once went out of her way to comfort a contestant who was feeling defeated.
On Wednesday's episode, Tatum accused Holly of being "fake" in front of bachelor Jimmy Nicholson.
"It is absolutely mind boggling to see how different she is behind closed doors,' Tatum said during a Q&A in front of Jimmy's family.
"It has bothered me a lot and makes me feel uncomfortable and I am quite over the fake facade that I feel is happening."
Holly appeared shocked and told Tatum she was "absolutely here for the right reasons".
The blonde beauty stormed off in tears before breaking down in a piece-to-camera interview.
"I just did not... I didn't see that coming at all. Like, I've never been nasty to any of these girls," she said.
"It's just almost like the second I'm forming a connection with Jimmy, people want to pummel me down."
Holly has already had a successful one-on-one date with Jimmy, as well as ample alone time together during cocktail parties - making her the current favourite to win.
According to the sites, the two women the pilot will take to the finale are Holly and Brooke Cleal.
The bets, however, differ when it comes to the second runner-up, with the former listing Lily Price to take out third place and the latter listing a tie between master key holder Jacinta Lal and dance teacher Ash Lawson.
The predicted winner, Holly, has been listed as a 1.50 on Sportsbet and a 1.10 on TAB.