Australian actor Liam Hemsworth was reportedly left mortified seeing his fiancé Miley Cyrus' racy performance at the MTV Video Music Awards.

Cyrus sparked controversy after she slipped into a flesh-coloured plastic bikini and performed a duet of Blurred Lines with Robin Thicke. She also placed a foam finger on her private parts as well as his.

"Liam really does care about Miley, but her racy new look and sort of ghetto attitude isn't exactly what he signed up for," a friend close to the actor told Radar Online, "Her VMA performance absolutely mortified him and he couldn't be more embarrassed. He doesn't really see anything sexy about what she did on stage."

Cyrus and Hemsworth have been dating since 2009, when they co-starred in the Nicholas Sparks film, The Last Song. Last year, on 31 May, Hemsworth proposed to Cyrus with a 3.5-carat Neil Lane diamond ring.

"It's not just Liam that Miley is pushing away…his entire team is urging him to part ways with her because she's nothing but negative for his reputation and career," the insider said, "Liam is a serious actor with a growing career, while Miley has just turned into a joke."

The couple made their lastest public appearance together, at the premiere of his film Paranoia at the DGA Theater in Los Angeles earlier this month.

"It's pretty much over. He knows he can't stay with her when this is who she's become. He doesn't want to babysit her anymore. He has to move on," the source said.

Previously, the former Disney star admitted that she is trying to stay out of the spotlight and is not interested to talk about her relationship status.

"We have a house together and dogs. It just seems right to be wearing this ring and to be committed. But we keep our relationship low-key and don't talk about it any more," the 20-year-old told to Elle UK magazine.