Khloe Kardashian's relationship with James Harden is already in trouble. The NBA star is being accused of cheating on his reality star girlfriend, who he has been "rumored" to be dating since June.

In an interview with New Idea, Australian student Rochelle Relf claimed she had a fling with Harden and also spent the night with the athlete last month during his visit Down Under. The affair reportedly happened after Kardashian and the Houston Rockets player took to a romantic Hawaii trip.

"Khloe was with James in Hawaii, then he flew to Australia and spent the night with me. He was charming, affectionate –he asked me to visit him in America and told me that he was a single guy," the 23-year-old said.  

Relf said she and Harden met unexpectedly at Sydney casino The Star while she was attending her friend's birthday party. She later added that she wasn't aware of his celebrity status until Harden asked his personal security to intervene when fans surrounded him.

Harden was reportedly openly affectionate with her in public until a security guard intervened and insisted that the two to stop touching one another. The two later went to Harden's hotel room where he showed her his popular Instagram account with 1.7 million followers.

"He kept checking I was single and asked if a boyfriend would come bursting through the door looking for me," she added. "I laughed and asked if any girl was going to come bursting through the door looking for him and he said no." 

As to why Relf decided to come forward about Harden extracurricular activities - she admitted to the magazine that she wanted to expose Harden because she doesn't want the "Keeping Up With the Kardashian" star to waste her time with him and be heartbroken.

"As a woman, I think we need to hear these things and she should know the truth... James is very good at making himself out to be a loyal person. He is Mr. Romantic and says what you want to hear. But he is in no way ready to be settling down, and it's no secret Khloe wants a family," she explained.

Adding, "Khloe has been through a lot... I'm saying all of this because she shouldn't be wasting time on this guy. He was happy to be entertaining girls in his hotel room and if he was my man, I would be chucking his clothes out on the street."

Harden and Kardashian began seeing each other shortly after he served as one of the coaches at Kanye West's birthday bash at the Staples Center last month.