“Gossip Girl” stars Penn Badgley and Blake Lively broke up after a three-year relationship, Us Weekly reported Wednesday.

The pair, who play one-time lovers in the hit CW television series, reportedly split up in September but “kept this news to themselves for a while,” according to a source.

“They’re professionals,” another insider told the magazine. “They’re still good friends and hang out on the set.”

Badgley, 24, first met Lively, 23, when both were working as up-and-coming child actors in LA.

Badgley previously commented on how much he enjoyed working with his girlfriend, saying, “Some would say it’s a double-edged sword, but in our case, we manage to balance it well.”

Insiders on the set of “Gossip Girl” said they were shocked by the breakup.

“Nobody on set had any idea,” said one. “They’re really just private.”