Teacher Julie McIlroy, 46, started chatting online with Allan Donnelly, 53, after skimming through thousands of pictures of eligible men on the Internet site.
They were amazed to discover they both lived in Cardiff - and were even more surprised when they found that they were neighbours.
"I was totally stunned. It was an incredible coincidence. The dating website could have put me in touch with someone anywhere in the world," the Sun quoted Julie, as saying.
The couple began seeing each other and went on holiday to Thailand and then to Cambodia and Morocco.
Electrician Allan has popped the question and the couple, who are both divorced, are planning their wedding for next year.
The father of two proposed mum-of-three Julie at a surprise birthday party for her at his home.
"I was amazed that we live so close. But it was my lucky day - Julie is right up my street," Allan said.