Nikki Bella is "heartbroken" by her split from John Cena just weeks before they were set to tie the knot

Nikki Bella is “heartbroken” by her split from John Cena just weeks before they were set to tie the knot.

Although Cena, 40, admitted in the past that he didn’t want to get married again — he was previously married to Elizabeth Huberdeau from 2009 until 2012 — he got down on one knee and proposed to Bella in April 2017. However, a source tells PEOPLE that he started getting cold feet as the wedding date drew near.

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“She never gave him an ultimatum. 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 insider says. “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 continues, “But in that case, he never should’ve proposed, let alone in front of millions of people. Now she’s heartbroken.”

“This was supposed to be the happiest time of her life,” the source adds. “He ruined it and blew everything up.”

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John Cena and Nikki Bella

The professional wrestlers’ wedding was set for May 5.

“It wasn’t going to be some showy Hollywood, over-the-top glitzy thing,” the source tells PEOPLE.

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The insider says Bella, 34, will be “fine,” but Cena has shown his real self.

“In wrestling there are two archetypes: faces and heels,” the source explains. “A face is a good guy, a hero, who you root for. A heel is a villain, who sometimes can seem like a good guy but then turns around and shows his true, evil colors. John Cena just revealed himself as the ultimate heel.”

The couple of six years confirmed their split with a statement shared to social media on Sunday, saying, “While this decision was a difficult one, we continue to have a great deal of love and respect for one another. We ask that you respect our privacy during this time in our lives.”

Cena seemingly opened up about the end of the relationship on Monday, tweeting, “Hardship, loss, and humility are extremely difficult waters to navigate, but perseverance thru them builds a strength to withstand anything life throws your way.”

While recently promoting his new movie Blockers, Cena told PEOPLE about how he already felt married to the Total Bellas reality star.

“People come up to me and say, ‘I love watching your wife on television.’ And I love that, so that happens to me 10 times before it would be a, ‘Yo man I love your work.’ It’s always, ‘I love watching your wife on television,’ ” he said, adding that he wished the two had tied the knot “yesterday.”

“I’m already ready to go there and it sounds nice hearing it,” he said of fans calling Bella his wife. “I know that we will have a wonderful future together because I love the way that sounds.”

Bella had already picked out her dream wedding dress — a gown from Marchesa — and decided on a black tie dress code for the big day.