Credit: Denise Truscello/

Sammi "Sweetheart" Giancola and Ronnie Magro are finito.

"They are done," a source close to the Jersey Shore duo tells, adding, there was "major tension" between them as they promoted the MTV hit's third season.

Indeed, another insider noted that the couple were "barely speaking to each other" during a Jan. 6 appearance on Good Morning America.

The couple's romance blossomed as they filmed the smash reality hit in Seaside Heights, NJ in 2009. Their combative relationship endured even after many bumps in the road, including Magro's numerous hookups with other women in Miami.

"I'm embarrassed about what I did to her," Magro said at the time.

Last week, Magro began Tweeting about "Single Ronnie."

For his part, castmate Pauly D told he prefers his pal single. "I love single Ronnie," he said. "When he's doing the relationship thing, I let him do his thing, I don't get involved,. When he's with Sammi he's a different person.  She's a difficult woman!