He complained to Financial Services Complaints Ltd (FSCL) which reviewed the case and alerted him to the situation.
He was adamant the relationship was genuine but was unable to get basic identification documents from the woman which were required by FSCL.
The woman could not provide him with proof of identity, her birth certificate or her passport.
FSCL said it was highly likely the woman was a fraudster who had skilfully groomed the man over a long period of time.
The independent disputes resolution service says it has received a number of complaints that centre around elaborate romance scams.
In the year ended June 30, it received five complaints about romance scams, up from one the previous year.
FSCL chief executive Susan Taylor said the numbers appeared small but it had since started to see more scams come to light.
"[We] suspect we may only be seeing the tip of the iceberg," Taylor said.
"The irony in these cases is that the complainants' issue is typically with the financial service provider who has refused a transaction, suspecting a scam, not with the scammer.
"Our complainants have remained under the illusion they are in a genuine relationship."
Another complainant had been sending money to a romantic partner facing extreme hardship in a civil war ravaged country and was outraged when the money exchange company declined a transaction.
A middle-aged Kiwi began talking to his "fiance" who lived in harsh conditions and faced extreme poverty five years ago. He regularly sent her money.
She went to collect the money from her local bank but was advised by staff that the transaction had been declined.
Complainants have remained under the illusion that they are in a genuine relationship.
The man contacted the money exchange company, "confused" at about why the transaction had been declined, and lodged a complaint to FSCL.
He said the money exchange had made a "cruel and arbitrary decision".
FSCL said this case was a typical internet romance scam.
Online safety organisation Netsafe defines romance scams as when a person pretends to be in a relationship with someone online for financial gain.
NetSafe says romance scammers can spend months building up trust with victims before they ask for money and are usually pretending to be someone they are not, using photos and identities of people they have found online through social media.
While it is hard to identify a romance scam, Netsafe says there are signs to watch out for: "moving quickly" where the potential scammer makes confessions of strong feelings within a short time of meeting online, talk of personal troubles that can be solved with money, requests, changes in communication styles and those who are hesitant to meet in person.
Some scammers are willing to play the "waiting game" before getting a pay-off, it says.
How to avoid a romance scam
• Be cautious about who you talk to online
• Don't respond to requests or hints for money
• Never send money to people you haven't met
• Avoid giving out personal details
