Miley Cyrus' controversial twerking display with Robin Thicke at the VMAs left her on-again, off-again fiancé Liam Hemsworth humiliated, and it could spell doom for the four-year relationship.

"The VMAs is the straw that will break him," a source predicted to Life & Style. "He wants out of the relationship."

Compounding matters for the worse, according to the source, is the chorus of voices from the Aussie actor's camp urging him to end things with the Hannah Montana star for good.