Bella announced the breakup on Twitter Sunday night.
"After much contemplation and 6 years of being together, Nikki Bella and John Cena announced today their decision to separate as a couple," she tweeted. "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."
No reason was given for the split. Bella and Cena were photographed this month kissing on the red carpet before the premiere of Cena's new movie Blockers.