Star Magazine is alleging that one of the biggest factors in Sean Penn and Robin Wright Penn’s recent separation is none other than Natalie Portman. In mid-March, there was a rumor that Sean and Natalie were caught making out at the Sunset Tower Hotel. This was just a few weeks after Sean had won his second Oscar, for Milk, when he purposely did not thank his wife. Now, Star is pushing the idea that not only were Sean and Natalie getting it on that one night, but they have been engaged in some kind of affair ever since.

There’s a source who is claiming all sorts of crazy things – like Sean is totally enamored with Natalie, that she “stimulates” him… mentally. I’ll bet. Honestly, I wouldn’t put it past Sean to try to hook up with someone like Natalie (young, smart, interesting, beautiful), but Natalie seems like too smart a girl to get involved with Sean. Still, Star makes an interesting case:

Just weeks after Star first broke the news that Sean Penn was caught making out with Natalie Portman at L.A.’s Sunset Tower Hotel, the Oscar winner filed for separation from his wife of 13 years, Robin Wright Penn. Now Star has learned that Sean, 48, and Natalie are still seeing each other!

“She stimulates him in ways no other person has, mentally or professionally,” says a source. “There’s a lot more there with Natalie than any of the other girls Sean’s been with.”

It was Sean’s mid-March indiscretion with Natalie that encouraged Robin, 43, to stop turning a blind eye to her husband’s philandering. “She was furious he was messing around with such a young star,” says an insider. “It made her sickly jealous.”

And with that, she told Sean she’d had enough and expected him to be a faithful husband and father. “She told him how it was going to be,” says the source. “But Sean did it his way and filed. He can be a real jerk like that. This will not be a smooth divorce.”

[During] Dean’s acceptance speech for his Best Actor win for Milk, he failed to mention his long-suffering wife, who sat just a few feet away, crying.

It was in the weeks that followed the award ceremony that Sean first met up with Natalie.

Will Sean be faithful to Natalie? Not likely, says the source. “He’ll still hook up with girls. It’s what Sean always does.”

[From Star Magazine print edition, May 18 2009]

Yes, I could totally see Robin being disgusted by Sean’s womanizing, especially if it’s with someone like Natalie. And I actually see Sean and Robin’s split going down the way Star describes – Robin accuses, gives an ultimatum, Sean balks and walks away from a twenty-year relationship without looking back. It fits with what I think of him – a cold, distant bastard. But was it all about Natalie? At most, I could see a smart girl like Natalie being pulled in by Sean’s obvious (but limited) genius, but she won’t stick around for very long.

Sean Penn and Natalie Portman are shown at Cannes on 5/25/08. Credit: WENN.com