As rumors swirl of Liam Hemsworth getting cozy with January Jones at a Grey Goose pre-Oscar party in LA on Feb. 23, Life & Style has learned that things between Miley Cyrus’ fiancé and the Mad Men actress got even more heated after they left the Chateau Marmont shindig.
“They went to a private house party, and right in the middle of the party, January was clinging to Liam, saying, ‘You’re so handsome,’” a guest reveals in the new issue of Life & Style. “He kept saying, ‘We can’t do this here.’ Then they left holding hands and went out in the hallway and were making out. She was wasted. It wasn’t good.”

PHOTO: See Miley Cyrus' incredibly thin body

Friends tell Life & Style that Miley is heartbroken over the news that Liam cheated on her with a true platinum-blond bombshell.

“Miley is freaking out,” a friend dishes to Life & Style. “She’s been telling her friends that she trusts him, but if she finds out the cheating claims are true, their engagement is over.”
Caught rushing into a waiting car together at 2:30 a.m. after partying at the Chateau, a source explains January is known for getting what she wants.

“When it comes to men, January just goes for it,” an industry insider tells Life & Style. “She doesn’t seem to care if they’re with someone or not. It’s like a challenge for her, a game.”
This isn’t the first time Miley and Liam's up-and-down relationship — which began on the set of their film, The Last Song, in 2009 — has suffered amid rumors of his wandering eye.

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In August 2010, his rep announced that he and Miley had ended their relationship after the rumors swirled that he’d gotten cozy with a bevy of beautiful blondes at a Newport Beach, Calif., party.
For more inside Miley and Liam’s rocky romance, pick up this week’s issue of Life & Style, on newsstands now!