The 26-year-old died on November 17 last year at the home he shared with his fiancee Ashleigh Wilson after experiencing Covid vaccine-related side effects over nearly a fortnight.
Nairn received the first dose of the Pfizer vaccine on November 5.
An autopsy report concluded that Nairn died of acute myocarditis - a known but rare side-effect, and with "no other cause" for the condition, said it was prompted by the vaccine.
Before the autopsy result, Wilson had told the Otago Daily Times it was frustrating not to have any clear answers, and she had decided to share Nairn's story.
She said he should have been made more aware of potential side effects.
If he had, he may have sought medical help sooner, she said.
Instead, he shrugged off his ongoing symptoms, which Wilson said he did not have before his first dose of the vaccine and put it down to stress.
Wilson said Nairn, a plumber, "started feeling heart flutters" a few hours after his jab.
"We put this down to stress as we were in the process of selling and buying a house and planning a wedding," she said.
"We never, ever considered the events that followed.
"Rory had heart palpitations regularly at night, and again, we thought this was stress.
"Twelve days later, Rory was up and down again during the night with his heart palpitations and an 'uncomfortable' feeling in his chest."
At 3am on November 17, the couple decided to go to the hospital for "reassurance".
But within minutes Nairn collapsed.
"It was really, really traumatic," Wilson recalled.
"I watched him die and I could not get to him. We were about to leave for hospital and he was in the toilet and I heard a thud.
"He had fallen, his body was blocking the door, his full weight was against it and I couldn't get it open.
"I could just see him through a crack in the door, I could see that he was gone."
Vaccinologist Dr Helen Petousis-Harris said overall the likelihood of developing myocarditis was about 10 in a million overall, but it affected younger males at a higher rate.
But even in the highest-risk group, she said the possibility of having something serious happen was "way way way" lower than with the infection itself.
"Myocarditis, that is inflammation, heart inflammation. It can be very, very dangerous and it has a spectrum of severity. The myocarditis that is being seen after the vaccine tends to be very mild and some data from the US shows just an average of one day in hospital."
- NZ Herald/Otago Daily Times
