Apparently not even love was strong enough to keep on-again/off-again former Meet the Barkers' co-stars Travis Barker and Shanna Moakler together.

"About a month ago, they separated again," a "source close to Moakler" told People on Thursday. "She moved out. As far as she's concerned, it's over. She loves him, but it's one of those relationships where they keep trying to make it work but it doesn't."

Moakler, a former Miss USA and Playboy model who appeared in the third season of ABC's Dancing with the Stars, and Barker, the former drummer for Blink 182 and current stick-man for Plus 44, were married in a Nightmare Before Christmas-themed wedding in 2004. 

Meet the Barkers, their Newlyweds-like MTV reality series, lasted two seasons. Broadcast between April 2005 and March 2006, the 12-episode series followed the daily happenings of Barker, Moakler, their two children (three-year-old son Landon and one-year-old daughter Alabama), and Moakler's seven-year-old daughter Atiana (whom she had with boxer Oscar de la Hoya). 

Barker originally filed for divorce from Moakler in August 2006 and the couple put their 12,000-square-foot Tuscan villa in Bel Air, CA -- where much of MTV's Meet the Barkers was filmed -- on the market for $8.5 million shortly thereafter.  But rumors began to circulate in early January that the couple had reunited when they were spotted "in full make-out mode" in Los Angeles.  Moakler eventually confirmed the rumors in late March when Barker threw her a 32nd birthday bash and the two were seen kissing again. 

Now it looks like the tumultuous relationship has come to an end yet again.

"[Moakler's] very upset. She gave this marriage her all. She really loves him," the source told People.

Stay tuned...