Lisa Spashett, who calls herself Aroha's second mum, said the Government had failed people like her future daughter-in-law.
She said there was nothing for them in New Zealand to look forward to or return to.
"As far as they are concerned, no, they [the National Government] hadn't done anything for them.
"I can tell you that straight up and that's why they are in Australia."
Ms Spashett said Aroha was working in Melbourne and she and Stuart were doing "really, really well over there".
Miss Ireland visited her estranged father, Jason Ireland, in Melbourne in 2010. She was so impressed she decided to move with her boyfriend.
She said her father had moved to Australia and "hasn't looked back".
Miss Ireland was a 2003 student on the I Have a Dream programme at Wesley Primary School.
The million-dollar programme provided academic help and life skills mentoring and offers a scholarship for tertiary study in New Zealand but a Herald report earlier this year showed more than a quarter of those who attended it have left for Australia.
In 2008, Prime Minister John Key famously took the then 12-year-old Miss Ireland to attend Waitangi commemorations with him.
She was teased at school after her Waitangi visit and was kicked out of Mt Albert Grammar School for misbehaviour.
Read more: Change on 'dead end' street