Duffy, 29, popped the question on the couple's four-year anniversary during a champagne picnic on Sydney Harbour, asking Bowen, 34, for her hand in marriage on the last page of a photo album celebrating their relationship.
Same-sex marriage is not legal in Australia but Duffy, a solicitor, said she grew sick of waiting, with three family members dying and both her parents experiencing illness in recent years.
"A few years ago we discussed getting married and I said I didn't want to do it until it was legal here, but I've obviously changed my mind," she told AFP.
"On reflection I just thought life's too short to be waiting around when it's something that you want to do."
The couple set a date -- November 23 -- and were considering a trip to New York for a honeymoon to rubber-stamp their union when neighbouring New Zealand became the first Asia-Pacific country to legalise gay marriage last month.
Instead of flying halfway across the world Duffy and Bowen now plan to take the three-hour trip across the Tasman Sea to make their lifelong commitment legal, before the major celebration they've labelled their "Sydney wedding".
Some 1,000 same-sex Australian couples indicated that they planned to travel to New Zealand to marry in a recent survey conducted by lobby group Australian Marriage Equality (AME), which described the new laws as a "game-changer" -- despite the fact that such marriages are not legally recognised back home.
"It's basically bringing marriage equality into our region, our part of the world for the first time," explained AME director Rodney Croome.
"We're as close as two countries can be and when New Zealand beats us at something it's very embarrassing. Australians don't like to be beaten by New Zealand."
Croome said the New Zealand vote had seen most Australian politicians change their perspective from denial of the issue to seeing reform as inevitable, with public support for change running at similar levels to that seen in New Zealand.
Tourism New Zealand (TNZ) has already moved to capitalise on the demand, launching a rainbow-themed "100 percent Pure Choice" campaign on social media based on its famous "100 percent Pure" slogan.
It also plans to run a contest for would-be newlyweds with a luxury New Zealand wedding as the major prize.
"It really caught us by surprise, the overwhelmingly positive response from Australia," said TNZ's Australia general manger Tim Burgess.
"It's created a real support base for New Zealand and we see a real potential there to bring in some good numbers."
New Zealand celebrants have received a steady stream of inquiries, mostly from Australians, since passage of the reform, which will come into effect on August 19.
Gay and lesbian Australians already travel abroad in significant numbers to marry, primarily to Canada, though Argentina and Spain are also popular, as are US states such as New York and Massachusetts.
The Australian government included a question on same-sex people wed overseas for the first time in its 2011 census, revealing 2,600 such couples -- a "great underestimate" according to Croome who said it was poorly explained.
Opinion polls consistently put support for gay marriage at between 60-65 percent but neither major party in Australia supports the move, which was explicitly banned under a toughening of marriage laws in 2004.
Duffy remembers the anguish of that moment, and of every wedding she has attended since where she says celebrants have been required to state that marriage is between a man and a woman, to the exclusion of all others.
"Every time I get this pain inside, it's just awful. You feel like someone's just punching you in the guts," she said.
Ten years later, she feels the mood is shifting.
"It's a matter of momentum and I think it's definitely going to change, it has to," she said.
The first step may be amending Australian law to recognise gay unions conducted abroad like Duffy and Bowen's -- the left-wing Greens party will present a bill calling for such a move later this month.
"Equality is now less than three hours away across the Tasman, but the sad thing is that gay and lesbian Australians will have to leave their marriage certificates at the customs gate," said Greens Senator Sarah Hanson-Young, who is proposing the bill.
"This shouldn't be a controversial idea and, as more and more countries recognise that marriage equality has found its time, Australia is becoming increasingly isolated in the international community."