He said that around December 2014, the man and his son had "had enough" of Boyd and asked her to leave.
Boyd then met Tong, who was addicted to methamphetamine, towards the end of 2015 and they lived in Dargaville.
On January 15, last year, Tong unlawfully took a car from Dargaville and he and Boyd decided to travel to the Weaver St property to pick up clothes she had left behind.
Tong kicked in the back door of the house, which was unoccupied at the time, and lit five fires inside and one in a shed.
A neighbour saw Tong coming out the front door calling Boyd to hurry up. Both then left in the stolen car parked away from the house.
Armed police rushed to the scene of the fire and the pair were later arrested in Hamilton.
Judge McDonald said both engaged in "fanciful" and nonsense behaviour of blaming each other in front of a jury who rejected their argument.
Boyd, he said, had been kicked out of the house and decided to take revenge.
The house was not completely destroyed but had to be demolished and temporary fences Crown prosecutor Catherine Anderson said a starting point of five-and-a-half years was appropriate and pointed to the fact both unlawfully gained entry into the house and used an accelerant to torch the property.
Tong's lawyer Kelly Ellis said there was no evidence of premeditation and submitted drug abuse and relationship breakdown contributed to his offending.
She said a starting point of four years was an appropriate sentence, given the fact Tong had no history for that type of offence.
Chris Muston, representing Boyd, said there was evidence the occupant of the house was aware she would come to take the rest of her clothes.
Boyd was sentenced to five years and four months in prison while Tong got five years' jail.
