Outside Memories Bridal Boutique in Dublin's Parliament Street, Niamh Herrity, 32, and Aoife Doyle, 34, who have been together for four years, were taking photos in their "Yes" T-shirts in front of the white wedding dresses in the shop window.
"We got our dresses last week, and this week we're allowed to get married. It's been an amazing, emotional couple of weeks," said Doyle.
They joked that as well as Adam and Eve, Aoife and Niamh -- pronounced "efah" and "neev" -- will now be permitted to tie the knot.
Their wedding date is set for December 17, but if the legislation has not passed by then, "we'll have a civil partnership then get a top-up," she added.
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While the final results were not due until later today, senior figures from both the "Yes" and "No" camps said largely Catholic Ireland was on the brink of becoming the first country in the world to green light gay marriage in a popular vote.
As Dublin's few gay bars prepared for a huge party later on, hundreds of cheering "Yes" supporters crammed into the grounds of Dublin Castle for the official results and were in celebratory mood as tallies came in.
Niamh Fitzgerald, 29, flew home from Birmingham in central England for the referendum and was the first to arrive in the castle grounds when they were opened exceptionally to mark the occasion.
"It's probably going to be the first election where the Catholic Church's power is waning," she told AFP.
"Everybody has a right to a religion but no one religion has the right to dictate to a country what our rights should be and that's why it's so important."
"They will grow up in a society where everyone is equal and they're going to learn that from a young age that it's not OK to discriminate," he said.