A Gronk return has been rumored almost since the day he announced his retirement this past spring ... and even after the NFL deadline passed for him to come back this year, people still think he might make a return next season.

But, when we got his smokin' hot GF out in NYC on Monday, she told us she doesn't understand why people think the ex-tight end is going to come back again.

"He's said like a hundred times that he's not coming back but everybody still asks. So, I don't know what to tell you any more!"

She added, "He's done."

As for his place in NFL history now that his career is officially over ... Camille tells us she has no doubts he's the G.O.A.T. when it comes to TEs!!!