According to Cunningham, he agreed she could keep living in the Appleby house as a tenant for a weekly rent of $250. The agreement was not written down but documents show McCormack paid rent weekly until June 16.
On June 17, Cunningham says, he posted his ex a notice of termination of her tenancy, with 90 days from June 24 to vacate the premises as he wanted to sell the house.
The last day of tenancy would be September 22.
She then stopped paying rent - which Cunningham said left him in a difficult position.
He was unable to access the premises to arrange a sale and had no income to pay off the mortgage on the house, which according to QV was valued in 2017 at $136,000.
He wanted the tribunal to end McCormack's tenancy for non-payment of rent and make an order for rent arrears.
But the tribunal decided it had no jurisdiction over the matter, because the Residential Tenancies Act 1986 did not apply if a premises was being used by a member of the owner's family.
While McCormack was no longer Cunningham's de facto partner, their daughter lived in the house and thus their rental arrangement was excluded from the Act, tenancy adjudicator B King said.
While Section 8 of the RTA says such tenancies can be brought under the Act, it must be agreed on in writing, King said. This had not been done in this case.
"The Tribunal therefore has no jurisdiction to make the Orders sought."
King added that under Section 65 of the Residential Tenancies Act the tribunal could evict a person if they were squatting in the house.
However, Cunningham would have to explicitly apply for the tribunal to make that order against McCormack.