11/30/2011 at 10:00 AM EST
After meeting her fiancé Roberto Martinez on The Bachelorette
last year, Ali Fedotowsky says she was ready to wed – and right away.
But after an 18-month engagement, the pair called it quits on Nov. 21 – and now, Fedotowsky is speaking out about what went wrong.
"I wouldn't be being truthful if I said this came out of nowhere," a tearful Fedotowsky, 27, tells PEOPLE for its new issue, on newsstands Friday.
"We definitely had been having problems. But I had always believed that we could work it out."
Despite slowing down wedding plans last year, and then twice more postponing plans to walk down the aisle with Roberto, 28, Fedotowsky says they did make an effort to stay together. Except, their arguments continued.
"We both realized we were unhappy more than we were happy," says Ali. "And we both deserved more."
For the full story on what went wrong, including the couple's explosive arguments and emotional final night together, pick up the new issue of PEOPLE, on newsstands Friday