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Newsflash: Having a three-way relationship when you are married doesn't work! Thank you Robin Thicke and Paula Patton for proving that tried and true marriage fact.

Open relationship? More like open to divorce!

Allegedly, the couple, who were high school sweethearts, split because he was having an affair with the lucky lady they were carrying on a consensual threesome relationship with, reports Starmagazine. Talking about blurring some lines!

The duo had been involved with the massage therapist, whom the publication refers to as "Jasmine," for two years. Patton was all fine and dandy with the menage-a-trois until she found out that Thicke and Jasmine had been carrying on their romance without her.

"Paula felt betrayed and humiliated by both Robin and Jasmine," said the insider. "These were two people she thought she could trust the most, but in the end everything backfired on her."

We're all about different types of relationships and the concept of, "to each their own," -- but seriously folks, carrying on a long term menage-a-trois seems like getting a FastPass to Split City. That kind of stuff never ends well for at least one of the people involved -- and in this situation it looks like it turned out poorly for all parties.