Thicke took to the piano during the show Sunday night to play a new tune, "Forever Love."
"I'd like to dedicate this song to my wife, and say I miss you, and I'm sorry," he said.
An audience member told Us Weekly that the singer, 37, "appeared to be crying during and after his performance."
In February, Thicke and Patton announced that they'd "mutually decided" to split after nearly eight years of marriage -- but since then Robin has been acting as if "mutual" doesn't apply to his half of the decision.
"For y'all that don't know, me and my wife separated, but I'm trying to get my girl back," he said on stage only days after the split went public. "She's a good woman."
He named his upcoming album "Paula," after the woman he met when he was only 14 and she was 15, in what he has said is an attempt to make it perfectly clear that the songs on the album are about her.
"All right, you got to help me try to get her back now," he said in May on the Billboard Awards stage before debuting the bluntly titled "Get Her Back." That after he'd thanked his wife when he won top R&B song honors for "Blurred Lines."
Thicke's twerky-grindy performance of his hit "Blurred Lines" with Miley Cyrus on the 2013 MTV Video Music Awards was only one of a series of Thicke's flirty public encounters with women-not-his-wife before the breakup. He was caught on camera last August at a VMAs after-party grabbing a woman's behind as well as in January at a Paris nightclub where he got close with another fan on the dance floor.
Patton has been publicly silent about it all, with the exception of telling Vanity Fair in May that "there’s a deep love there -- always was, and always will be.”
Perhaps there's still hope: As of Monday, her Twitter bio still includes the declaration, "Actress, mom, wife of the amazing, brilliant, genius @RobinThicke!"