TEEN star Miley Cyrus is putting on a brave face following her shock split from boyfriend Liam Hemsworth.  The actress, 17, was pictured smiling while filming her new movie, LOL: Laughing out Loud, in Detroit. The comedy, about a teenage girl, her friends and dating in the age of Facebook, also stars Demi Moore as Cyrus’ mother. Cyrus and Hemsworth — who met when they shot family drama movie The Last Song in 2009 — apparently decided to go their separate ways when Liam lost his temper after seeing Miley straddling a mystery man on the set of LOL in Detroit.

“Miley is devastated,” a source said. “She really thought Liam was ‘The One’.

“Although she did put her career ahead of they’re relationship, she made it clear it to Liam he wouldn’t always come second.

“She’s hoping they’ll be able to sought things out.”

However, it seems Liam may have already found himself a new woman — the Aussie hunk was seen getting cozy with a gorgeous blonde named Katy, 26, at the Shorebreak Hotel in Huntington Beach, Calif., on Aug. 7.

“She and a girlfriend approached him at the bar,” a source told American’s Star magazine.

“Girls were fawning over him all night, and he was clearly loving the attention, but he really took a liking to her.

“They were all throwing back beers and having a great time.

“Later, he suggested that they all go back to the Doubletree hotel, where they were staying, to keep the party going.

“Miley’s name was never brought up. He certainly didn’t mention her.”

Liam also exchanged numbers with Katy, the source said, and he “promised to call” her.

“They definitely had a strong connection.”