The 29-year-old actress sat down with ET in September to discuss her new memoir, Sorry Not Sorry, in which she gets extremely candid about her personal life. At the time, Rivera said that Dorsey had always been "the One" -- though she didn't see it at first.
"I have always kept a flame for him," she admitted, referring to her feelings after their initial 2010 breakup. "In between boyfriends or whatever, if I was single for a minute, I would always answer his emails and go see him."
Rivera's last Instagram with Dorsey, 33, came 11 weeks ago when he was working on Pitch. The Glee star captured a screenshot of Dorsey FaceTiming with her from the set.
Meanwhile, Dorsey's last photo of Rivera was a throwback to celebrate their anniversary 17 weeks ago.
When Rivera's engagement ended with Big Sean in April 2014, reps for the "Blessings" rapper told People that Sean was the one who called off the wedding.
"The recent rumors and accusations reported by so-called or fake sources are simply untrue," the rep told the magazine. "Sean wishes Naya nothing but the best and it is still his hope that they can continue to work through their issues privately."