Bristol Palin-Levi Johnston Engagement Off; Briana Plum Facebook Pic to Blame!

It looks like the second engagement of Bristol Palin and Levi Johnston is off, but that the rumor of him knocking up his ex-girlfriend is not the reason.

His flirting with another ex-girlfriend is!

Bristol, 19, called off engagement #2 to Levi, 20, last week following a huge fight over one of his ex-girlfriends - and we don't mean Lanesia Garcia.

Garcia was outed as Levi's possible second baby mama this week, but new reports say that the Playgirl model is not the father of her unborn child.

Luckily for our boy, he wasn't the one among the "three potential fathers" to have impregnated Lanesia during the probable week of conception.

But Bristol Palin still has beef with him - and Briana Plum.

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Levi Johnston apparently got naked a lot in between his two engagements to Bristol Palin, and we're not even talking about his Playgirl photo shoot for once.

"Lanesia and Levi have dated off and on over the past few years but he's not the father of that baby," says a source to E! Online. "Lanesia's other ex-boyfriend is the father. She's not the reason that [Bristol and Levi] broke it off."

That would be Levi's other ex, Briana: "There was an interview with her and Bristol wasn't happy about things she said. There was also some picture on Facebook of him and Briana and Bristol just said, ‘Let's hold off on the engagement.'"

Neither Palin nor Johnston have confirmed this, but the parents of 19-month-old Tripp just got engaged again a few weeks ago, landing them on the cover of Us Weekly amid rumors of shopping a reality show featuring their young family.

Guess even a huge paycheck can't keep some fake relationships intact.

Can Bristol and Levi still make it work?