John Cena, Nikki Bella break up details revealed

WWE stars John Cena and Nikki Bella split: What went wrong?

Just days before their wedding, WWE stars John Cena and Nikki Bella called it quits. What went wrong between them? Insiders say Cena got cold feet.

Nikki Bella and John Cena shocked fans when they announced they ended their engagement just weeks before their scheduled May 5 wedding.

The WWE stars called their split a "difficult" decision in a joint statement on Sunday.

"While this decision was a difficult one, we continue to have a great deal of love and respect for one another," the couple said via Instagram. "We ask that you respect our privacy during this time in our lives."

The couple began dating in 2012 and Cena, 40, proposed to his longtime love at WrestleMania 33 last year. Fans were stunned by the news of the breakup as the former lovebirds had recently gushed over their upcoming nuptials.

At a March 23 press conference for WrestleMania 34, Cena recalled proposing to Bella.

"When a man finds the woman of his dreams and wants to say that he loves her and for the world to know," Cena said before calling up his then-fiancee. "Nicole, want to come up here for a second please?"

Cena hugged Bella and through tears told the crowd that WrestleMania -- and seemingly Bella -- means "everything to me."

Bella told Fox News in August that Cena calls her his "bride."

"The only thing that's changed [since the proposal] is he'll text me now saying like, 'I'll miss my bride.' So now he's using the term bride and fiancee which I love," she said at the time.

So what went wrong?

Cena, who was married to Elizabeth Huberdeau from 2009 to 2012, had previously spoken about his desire to not marry again. Despite getting down on one knee in front of the world to ask Bella to marry him, insiders told People he got cold feet as the wedding date approached.

"He talked a really good game about having changed, about having his priorities straight, about knowing what’s important, and that it was her. But as the day got closer, it was like he just went back to who he’s always been — which is someone who puts himself first, always," the source told the magazine. "He’s an incredibly dedicated, driven, ambitious guy. And for the longest time he said he didn’t think he had room in his life for a spouse or kids. It seems like in the end that was still the truth."

The source added that Bella is "heartbroken."

"He never should’ve proposed, let alone in front of millions of people. Now she’s heartbroken."

Cena did hint at trouble in an interview with Us Weekly last week.

"Relationships are hard. Don’t ever think that love is easy. Love is beautiful, but we’ve had to come to the realization after being together for five years that love is not easy," he said.

Multiple reports indicated that the duo's busy schedules led to their break up.

Fox News' Steve Credo contributed to this report.