A GAY couple who fell in love after meeting 15 years ago on Gay.com have declared they will vote "No" in the upcoming postal vote on same-sex marriage.

Ben Rogers and Mark Poidevin, from Wollongong in NSW, told ABC TV's 7.30 Report last night they want to preserve the traditional definition of marriage.

"If we make one exception for one community, that being the same-sex couples, where does it stop?" Mr Poidevin, a staunch Catholic, said.

Their unexpected admission sparked backlash online, with same-sex marriage supporters accusing them of being "self-loathing" and "homophobic".

But Mr Poidevin hasn't always opposed the idea of same-sex marriage, having popped the question to his partner five years ago.

"At the time Ben said it wasn't for him, that he didn't believe in it, and I said, 'When the laws change, would you like to?'" he said.

Couple Ben Rogers (left) and Mark Poidevin oppose gay marriage. Picture: ABC 7.30
Couple Ben Rogers (left) and Mark Poidevin oppose gay marriage. Picture: ABC 7.30

When Mr Rogers rejected Mr Poidevin's proposal, he told him he had never thought same-sex couples should get married.

"I just explained to him, 'I don't think it's my cup of tea,'" Mr Rogers said. "It's not something I had ever envisioned."

They said even if same-sex marriage is legalised in Australia, they won't tie the knot.

The couple said heated debate on both sides leading up to the postal survey could result in a shock result if the vote goes ahead - like the election of US President Donald Trump or Brexit.

"The campaign's gotten nasty on both sides and I think the comments that I hear are, 'You're a homophobe if you don't support gay marriage,'" Mr Poidevin said.

"I'm a gay person here that's coming out and saying, 'Well, no it's not. It's your right to have a view, your right to have a view either way and people should be respected.' You're not intolerant if you don't support a view."

Social media users slammed the duo, saying all couples should have the right to marry.

This week the High Court will hear two challenges from the "Yes" campaign against the Government's $122 million postal survey.