Miley Cyrus may have no problem with her much-talked about performance at the MTV Video Music Awards on Sunday, Aug. 25, but one very important person in her life does -- fiance Liam Hemsworth. According to a source close to the actor, the pair is "just weeks away from calling it off permanently."

"He is over her and wants to make a clean break," the source tells Us of the Australian hunk. "No more back and forth."

Another insider adds that Hemsworth found Cyrus' performance, in which she rubbed up against Robin Thicke and made crude gestures with a giant foam finger, "mortifying."

Hemsworth, 23, and Cyrus, 20, have been on and off in recent months, and though the young couple reunited on the red carpet on Thursday, Aug. 8, the pair "acted as if they were strangers," a source told Us at the time.

At present, the pair still reside together at Cyrus' home in L.A.'s Toluca Lake, but the pair are more like roommates than lovers, another source notes. "They're not even sleeping in the same room," the source said.

Get all of the latest details on the couple's hot-and-cold relationship in this week's Hot Stuff video, as explained by Us Weekly's entertainment director Ian Drew and special guest, singer Matt White.

Also in the roundup: Clint Eastwood and estranged wife Dina's spouse swap, Charlie Hunnam's initial skepticism about the Fifty Shades of Grey role, Dancing With the Star's new pregnant pro dancer and more.