The wrestlers announced the end of their engagement in a joint statement

John Cena is reflecting on the end of his six-year relationship with Nikki Bella.

“Hardship, loss, and humility are extremely difficult waters to navigate, but perseverance thru them builds a strength to withstand anything life throws your way,” he tweeted Monday — the morning after the wrestlers announced the end of their engagement in a joint statement.

Cena, 40, and Bella,, 34, got engaged in April 2017 on live TV during a match. Their destination wedding was scheduled for May 5. (In October, they announced that they’d changed the date due to their schedules.)

A source told PEOPLE that the Blockers actor started getting cold feet.

John Cena, Nikki Bella
Credit: Phelan M. Ebenhack/AP

“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 said, adding that he “never should have proposed” and that Bella is “heartbroken.”

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

Their relationship wasn’t without troubles: Her E! reality show Total Bellas documented the couple clashing over Bella’s desire (and Cena’s refusal) to start a family.

“Would I hope John would one day want kids? One hundred percent,” she told PEOPLE shortly after the couple’s engagement. “But I have come to that decision to being okay with it, that I won’t be a mom. I will be the greatest aunt ever.”