Like all relationship breakdowns, it's hard to know exactly when or why the All Blacks and Wallabies lost their mutual respect for one another, and allowed their rivalry to turn septic.
But they have reached the point they didn't want to - full of resentment, ill-feeling and bitterness about how the other has behaved.
'Spygate' has been the bridge to ruin.
Whatever the intention was of whoever put the listening device in the All Blacks' Sydney hotel room in August last year, one perhaps-unintended outcome has been to bring the relationship between Australia and New Zealand close to breaking point.
Now, both feel the other crossed some sort of line.
The All Blacks see themselves as victims, no matter who it turns out was behind planting the device. Their privacy was breached, their camp penetrated and the invasion feels like a violation.
The Wallabies feel like they are the accused. That, while the All Blacks said precisely nothing about who they thought was responsible, the Wallabies think they implied it by "leaking" the story on the morning of the first test on August 20 last year.
"I would say they caught me a bit offside with the accusation that we tried to bug them," Cheika said, after the third Bledisloe Test last year, when asked whether the Wallabies' relationship with the All Blacks had turned nasty.
"Really? Hello? Honestly? They had that the whole week. That showed a lack of respect.
"I wouldn't be smart enough to get that sort of stuff organised. I am too busy working on my own thing."
Cheika's claim that the All Blacks had made an accusation was not well received in the New Zealand camp. Their take on events was radically different.
New Zealand Rugby reported to the New South Wales police that they had found a device, because they were duty bound under World Rugby's integrity guidelines to do so.
NZR say there was no intent to imply or insinuate guilt based on the timing of when they did so. In fact, NZR went to considerable lengths to deter the Herald from publishing the story on the day of the game.
Cheika's outburst last year felt to NZR like a punch to the side of the head and so too did the ARU's hasty response to the news that an arrest had been made in connection with Spygate.
The statement from CEO Bill Pulver was almost vitriolic - as if he was genuinely pleased that the man arrested worked for the All Blacks.
Spygate has been a wrecking ball, but the relationship between the two nations could have been smashed apart by a far less forceful weapon. Plenty had happened over the past 12 years to take things to the brink of breaking point.
The decision by the ARU in 2005 to vote for Japan's and not New Zealand's 2011 Rugby World Cup hosting bid was maybe the start of the genuine bad feelings.
The arrival of Robbie Deans as Wallabies coach - the day he missed the All Blacks job - fostered a cold war environment that was exacerbated by the relentless feud between Quade Cooper and Richie McCaw.
Generally, rather than specifically, the All Blacks felt that too often Wallabies players and coaching staff spoke with a lack of respect between 2011 and 2014. There was never much acknowledgement for the achievements or standing of New Zealand rugby, just promises of a Wallaby revival.
Given the All Blacks have held the Bledisloe since 2003, and have won 31 of the last 39 tests and drawn two others, the lack of respect was hard to fathom.
The arrival of Cheika as coach in 2015 accelerated relations towards open hostility. The first Bledisloe on his watch saw the Wallabies play far better, but also indulge in what appeared to be an obvious strategy of subjecting the All Blacks to niggle and cheap shots.
That became entirely apparent in the Rugby World Cup final, where there were several late, high tackles, jersey holding, line blocking and a blatant stamp by David Pocock on the face of McCaw.
The enormity of the occasion, the drama of the game and the attacking qualities of both teams meant much of the nasty stuff escaped the attention of those watching, but the players all knew what was going on and the All Blacks weren't happy about it.
It was hard for them to respect a side that played so hard in the grey areas and it only got worse last year.
The second test in Wellington was shocking. The Wallabies came with one plan - to play the All Blacks off the ball - and the test was marred by endless scuffles and heated exchanges.
It was ugly and yet, curiously, Cheika chose to berate referee Romain Poite after the game, suggesting the French official had treated captain Stephen Moore with a lack of respect.
Cheika then, wrongly, suggested All Blacks coach Steve Hansen had illegally met with the referee before the test, fuelling the bad blood further.
"We knew they would come out a lot more physical and potentially with a bit of niggle," All Blacks flanker Sam Cane said after the test. "The way they went about it was probably what caught us off guard just a fraction, but we acknowledged pretty quickly that that was how they were going to play.
"In a funny way, it's a good thing when you realise the opposition are playing like that because it means they're not really focused on their footy as much.
"And as long as we worry about playing footy and executing our stuff right, then there should be some answers and I suppose that's how the game played out."
Maybe there is a way back to a more cordial footing, but with Adrian Gard, the chief security contractor used by the All Blacks in Australia, due in court next month to face charges around Spygate, it's hard to see how peace will break out.
This year is supposed to be all about the Lions, but they may end up as the undercard to what is shaping as an explosive and hugely fascinating Bledisloe series.