As in any messy split, the deeper the love, the worse it hurts.
"I had mixed emotions coming in, because I know how special these fans are," Favre said Sunday night after beating the Packers 38-26 in his first game in Green Bay since signing with those hated Minnesota Vikings. "I want to lead this Vikings team to a Super Bowl, believe me, I do. And I will do everything in my power.
"But I also know the Packer fans are what makes this organization so special, unique, and that will never change. How could you not miss that?"
Wisconsin has a bond with the Packers unlike anything else in pro sports and, when he was here, Favre was beloved by the entire state. It wasn't just that he rejuvenated the storied franchise, bringing the Lombardi Trophy back to Titletown after the team wallowed through two decades of mediocrity - or worse. Or that he turned Cheesehead, a derogatory nickname favored by residents of neighboring states, into a term of endearment and pride.
To Wisconsinites, Favre was family.
He liked to hunt and, in the early years at least, drink a beer or two. He preferred jeans and flannel shirts to suits. And game after game, year after year, no matter what personal crisis he faced, he did his job.
"He was," Jo Sedar said, "one of us."
Which is what made Sunday so gut-wrenching. Favre didn't just leave - the hows and the whys will be debated long after Favre really does retire - he went to the one team that Packers fans detest. Imagine John Elway playing for the Raiders or Derek Jeter going to the Red Sox. Even Michael Jordan knew better than to play for Detroit when he left the Chicago Bulls.
A plane trailing a "Retire 4 Good" banner circled Lambeau in the hours before the game, and Favre was greeted with a long, loud chorus of boos when he jogged out for the game, the last of the Vikings to take the field. Oh, he heard cheers here and there, but they were largely drowned out by whistles and boos anytime he got close to the ball.
There were shirts calling him everything from "Traitor" to "Judas" to "Drama Queen." One fan carried a poster with "True Legends Don't Wear Purple." Behind the Vikings bench, someone hung a "Welcome Back to Lambeau Field ... B-R-E-N-T" sign.
"It's like going into church on Sunday and the priest says, 'Everybody go home, Jesus has now sided with the devil,"' said Tom Fields, whose Favre jersey now has "JUDAS" on the back and big red slashes through the 4s.
Asked if he was surprised at the reaction, Favre said, "Sure, I would have loved ..." and then paused.
"It was about what I expected," he said.
But it's impossible to ignore what Favre meant to the Packers, and the conflicting emotions were everywhere. Some fans wore Favre's Vikings jersey beneath their Packers jackets. There were half Minnesota-half Green Bay jerseys. Other fans simply wore their old Green Bay No. 4s.
A smaller sign near the Vikings bench said, "Thanks 4 the Memories," and another proclaimed Lambeau "Brett's Field."
"I'm having mixed emotions," admitted Robert Barranco, who wore a green Favre jersey while his wife, Martha, had on the newer, Vikings edition. "I'm a die-hard Packers fan, but I also want him to do well."
Favre had said he didn't expect to be overly emotional, that facing the Packers last month for the first time was tougher than coming back to Lambeau. But as he got closer to Lambeau, he was flooded by a swirl of emotions. He grew up here, as much as he did in Mississippi.
"Cheers, a couple fingers. Some people, not exactly mooning ..." he said of the reception when he arrived. "That part was a little weird."
For much of the game, Favre seemed clinical, almost detached. He showed no reaction to the boos, no acknowledgment this was a place where he was once so revered, so accomplished that they've already decided to retire his number. It could have been any of the hundreds of other road games he's played, in any of a dozen other stadiums.
As the game wore on, though, Favre couldn't contain his feelings.
He sprinted downfield after connecting with Bernard Berrian on his fourth and final touchdown pass, holding his index fingers high in the air. He hugged Berrian so tightly he lifted him off the ground, then hugged and slapped hands with anyone in a white jersey that was within arm's reach.
"I was part of some pretty good games here as a Packer. This is pretty high up on the list," Favre said. "It was pretty awesome to be a part of."
When the last second ticked off, he raised his hands in triumph and bearhugged several of his Vikings teammates before strolling to midfield. There, he exchanged a handshake and pleasantries with Packers coach Mike McCarthy and Aaron Rodgers, his replacement. He also embraced Greg Jennings, and shared a long hug with Donald Driver, his favorite receiver in Green Bay.
He pumped his fists when he finally left the field, ignoring one last chorus of boos.
"I've never been one to rub it in anyone's face," Favre said. "The guys I played with as a Packer, I've got a lot of respect for them. As I do for the organization and the fans."
But he belongs to somebody else now. How fans - and even Favre, to some degree - will reconcile that with their memories of the good old days is a task that will take much longer than one afternoon.
"Although I wasn't expecting a standing ovation, I know what I've done, what I stand for," Favre said. "What I've done here speaks for itself. What I was a part of was awesome. That will never change."