Robin Thicke & Paula Patton threesome sparks divorce? 'Open marriage' ignites 'Blurred Lines' cheating, sexy massage therapist hook-up leads to split?

Back when they were still a couple, rumors suggested that Robin Thicke and Paula Patton practiced an "open marriage." Apparently, the "Blurred Lines" crooner would hook-up with his stunning wife and another sexy mystery girl - at the same time! But things eventually got out-of-control, and Thicke actually started cheating on Patton. That's when she called it quits. Is this all Lana Scolaro's fault?

Maybe not...

The shady gossip tabloid Star reports:

"...It was one ongoing affair that upset Paula so much, she could never forgive him — mainly because she had been involved with the 'other woman' as well!"

Two years before their split, Thicke and Patton allegedly enjoyed a sexy (ongoing) threesome with a massage therapist named "Jasmine." But just last summer, the "Baggage Claim" starlet caught Thicke fooling around with this third-wheel - behind her back. And that just didn't fly.

There's a photo (via MediaTakeOut.com) of Patton partying with this rumored mistress. The caption reads:

"Three's a crowd. 'Jasmine' and Paula at a New Year's Ever party in 2012. A close source says Paula invited Jasmine into her marital bed to please Robin, who rewarded his wife's generosity by seeing Jasmine behind her back."

Ouch.