Rumors of a broken engagement have been plaguing fiances Miley Cyrus and Liam Hemsworth.  Miley is denying relationship trouble while Liam's escaped to Australia.  Now, allegations of cheating have surfaced, and a Mad Men star may be at the core.

The young couple, engaged since last year, have not been photographed together in months.  Miley has even been spotted recently without her engagement ring, while Liam has reportedly been seen getting cozy with actress January Jones.

 

 

 

According to reports, spies caught Jones and Hemsworth at a pre-Oscars party on February 23 holding hands and making out.  The pair left the event together, according to Life & Style.

 

Geoff Burke, Getty Images

January Jones got hit with a barrage of questions about the alleged affair when paparazzi met her on Friday at LAX where, according to TMZ, she didn't exactly jump to deny the rumors.

Miley took to Twitter last week to say she was tired of the L.A. scene and all the photogs, and that she was taking a break from social media.  It was around that time that Hemsworth took off to his native Australia for some alone time.