One in three partnership visitor visas are being declined as immigration advisers warn that officials are taking a tougher stance on visa cases.
The number of rejections among the partnership category of visitor visa has increased from 14 percent a decade ago to 35 percent last year.
An immigration lawyer says the human toll could be considerable if the government decides to cap the number of partnership visas.
The Association for Migration and Investment said there had been a shift in the way applications were dealt with, and a tightening of how appeals to the immigration minister were handled.
Its chair June Ranson said Immigration New Zealand was adopting a more cautious approach to visa applications.
"Some of them are quite unfair, quite unjust because it's not transparent," she said. "We've seen there definitely has been a shift in the way applications are being looked at.
"I do think that they have tightened up a lot in the partnership area, it's all about them being genuine relationships and just because a person has a joint bank account - it's only part of the evidence that's being produced.
"They need a lot more than that because people do things as a matter of convenience to be able to get through the system."
People turned down for visas when they are abroad should have the right to have their case reviewed by an independent body, she said.
Steve Razos met his wife Krystel in the Philippines four years ago and they have a two-year-old son, Johnny, together.
Immigration New Zealand said they misled them when they broke up temporarily, and cancelled her visa while she was visiting family in the Philippines.
She supplied false and misleading information and it was not satisfied they were in a genuine and stable relationship, it said.
Mr Razos visits his family regularly but he has a 10-year-old son and business in New Zealand so cannot live there.
He estimated they had spent $30,000 or $40,000 in travel and legal and immigration costs.
Three visitor visas and one partnership visa had been declined since then and there were no legal avenues for them to appeal, he said.
Associate minister, Kris Faafoi, had declined to review the decision as his predecessor looked at the case last year.
"The minister, for whatever reason, has decided to not even look at it so I'm really baffled about that," he said.
"There's a child involved, we're a married couple, clearly we've been together for a long time now - we're not going anywhere, we love each other and the only thing that's stopping us is them.
"It's just so frustrating that we just keep getting met with walls put in front of us all the time."
Immigration lawyer Simon Laurent said partners had avenues to appeal temporary visa rejections if they were already in New Zealand, but not if they were abroad.
Fears of an upcoming change on partnership visas have been sparked by a government request for officials to report back on family categories.
The human toll could be considerable if the government decided to cap the number of partnership visas, meaning partners and spouses could wait years to be reunited, he added.
"Myself and colleagues in the industry have noticed a tougher stance on the criteria that are being applied to partnership visas both work and residence where cases which would have been approved without question in the past are now being more rigourously questioned," he said.
Immigration New Zealand area manager Marcelle Foley said it needed to be satisfied that the relationship was genuine, stable and likely to endure.
"Every application is assessed very robustly to maintain the integrity of the immigration system," she said. "There have been no recent changes to immigration instructions against which such applications are assessed."