Why John Cena Doesn't Want to Become a Dad — and How He Gave Nikki Bella 'False Hope,' Source Says

A source tells PEOPLE the professional wrestler is "almost singularly focused on his goal of being a mega-famous performer, entertainer and actor"

John Cena and Nikki Bella were together for six years — and throughout their relationship, the former fiancés struggled to get on the same page when it came to their opposing viewpoints on becoming parents.

Though Cena, 40, was steadfastly against having children from the get-go, Bella, 34, was initially vocal about her desire to be a mother — though she claimed she eventually came to terms with the idea of not having kids.

So what makes Cena so reluctant to become a father? According to a source, the professional wrestler is “almost singularly focused on his goal of being a mega-famous performer, entertainer and actor.”

“It’s not fair to a kid to bring them into the world if you’re not prepared to be focused on them, and he’s just not,” says the insider. “He doesn’t want to be an absentee parent and he doesn’t see how he wouldn’t be given everything he wants to do in his career and in his life.”

According to the insider, another reason Cena may have for not wanting kids is possibly due to his time spent with terminally ill children. (The WWE community works closely with Make-A-Wish, and Cena has personally granted more than 500 wishes.)

“To contemplate bringing a child into this world who could then get hurt or sick — it would be more than he could take,” says the source. “But you can’t live your life according to a possible worst-case-scenario. His brother has health problems — but if anything, that should just show him that these things can be manageable, because John does help with that stuff a lot.”

“Look, it’s his prerogative to not want kids,” adds the source. “But in that case, all of this should have stopped so long ago. They should have broken up after a year. And really that’s on both of them: She shouldn’t have tried to twist herself into someone she’s not just to please him. And he shouldn’t have given her false hope that he was going to change.”

Interestingly, while promoting his latest movie, Blockers, Cena admitted that playing a dad in the film had “certainly changed” his perspective on fatherhood.

“The movie helps with that, certainly my perspective on life helps with that, working on my relationship with my bride to be helps with that, so it’s amazing what you can accomplish if you just sit down and talk with people,” he told PEOPLE. “So I’ve done a lot of that.”

RELATED VIDEO: How John Cena ‘Convinced’ Nikki Bella That He Was a Changed Man Before Ending Engagement

Cena and Bella announced their split on Sunday with a statement released via Twitter: “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.”

The breakup came just weeks before they were set to tie the knot at a May 5 destination wedding, and a source told PEOPLE this week that Cena started getting cold feet as the date drew near. (The actor, who was previously married to Elizabeth Huberdeau from 2009-12, has admitted in the past that he didn’t want to get married again.)

“He talked a really good game about having changed, about having his priorities straight, about knowing what’s important, and that it was her,” said the source. “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. 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 former couple’s romance unfolded on E!’s reality shows Total Divas and Total Bellas — and a TV special about their wedding was set to air in July. The concept has since been scrapped, but their relationship will still be a plot point in Total Bellas, which returns May 20.