Is there trouble in paradise for Liam Hemsworth and Miley Cyrus? New reports suggest that her hunky Australian fiancee may have a wandering eye!

Star (via Radar Online) reports that Hemsworth got hot and heavy with actress January Jones at a pre-Oscars party at Chateau Marmont. “It looked like they had some hot chemistry,” a witness at the party claims. “They were all over each other – and they even kissed!”

While Hemsworth supposedly got his flirt (and maybe more) on with Jones, who has previously been linked to taken men, Cyrus partied it up at the Elton John AIDS Foundation gala on her own, where she was described as being "all over the place."

For her part, Cyrus, who has been open to gushing about Hemsworth and their relationship in interviews and on Twitter, has remained mum about the alleged cheating scandal. In the past she's adamantly defended the strength of their union -- and even referred to her fiancee as her "hubby" -- so time will tell. This may well just be a bunch of tabloid rubbish ... we hope!

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