Carolyn Dare Wilfred (64) left New Zealand last September after her business visa expired, leaving behind stateless husband Harmon Wilfred, who lives just south of Christchurch.
Mr Wilfred, who claims to be a former CIA contractor-turned-whistleblower, renounced his US citizenship in 2005 following threats to his personal safety and freedom.
As Mrs Dare Wilfred left, border officials slammed the door.
Immigration New Zealand suspended her visa waiver which allows Canadians to visit for three months, a decision now being investigated by Chief Ombudsman Peter Boshier.
Mr Boshier's office has written a "please explain" letter to David Smol, the head of the Ministry of Business Innovation and Employment, which runs the Immigration Department.
The Ombudsman's letter outlines Mr Wilfred's concerns that the visa waiver suspension is unreasonable. Immigration's refusal, in May, to grant her a temporary visa stated there was an unacceptable risk Mrs Dare Wilfred would overstay.
An Ombudsman's office senior investigator, David Scott, wrote to Mr Wilfred last month and said: "I have requested a report [from Mr Smol] on the concerns you have raised.''
Mr Wilfred (66) told the Otago Daily Times his wife had every incentive to follow Immigration's rules.
She hopes to return to New Zealand and invest millions of dollars in at least three Kiwi businesses.
Mr Wilfred, who lives in Lincoln, said the Ombudsman's investigation was encouraging and the couple, who have lived in New Zealand since 2001, were hopeful that, after 10 months apart, they would be reunited.
Their 18th wedding anniversary is early next month.
"For us to be apart for this period of time is really difficult for both of us,'' he said.
Mrs Dare Wilfred said from Canada: "All I know is I miss my husband, I miss my pets and I want to come home. It's just been too long - too much.''
In an emailed statement, Immigration NZ area manager Darren Calder confirmed it had been notified of Mr Boshier's investigation.
"As the Chief Ombudsman is now investigating, INZ is unable to make any further comment.''
Mrs Dare Wilfred, whose application for an "investor plus'' visa has been declined by Immigration, is asking for a Canadian court order forcing her brothers to buy her stake in giant food company Dare Foods.
By one calculation the stake could be worth at least $C35million ($NZ38million).
Discovery in the Canadian case has been completed and mediation has been ordered.
Mrs Dare Wilfred has appealed Immigration's rejection of her investor plus visa application to the Immigration and Protection Tribunal.
The Wilfreds, who believe their harsh treatment is the result of a government grudge, have also appealed to politicians, but without joy.
Justice Minister Amy Adams is their local member of Parliament.
One of Ms Adams' senior staff members, Sharon O'Callaghan, wrote to Mr Wilfred this month saying: "Unfortunately members of Parliament are not able to intervene in Immigration processes so I am sorry to advise that on this occasion Amy is unable to assist.''
Associate Immigration Minister Craig Foss' office said last month it "now considers this matter closed''.
