Sienna Miller behind Sean Penn’s divorce

Sienna Miller may be the catalyst for Sean Penn and Robin Wright-Penn’s divorce. Sienna and Sean were spotted together partying in a New York hotel suite while Robin was home with the kids. NY Daily News reports:

“Sienna was sitting on Sean’s lap,” according the source. “She was dressed very sexily. She had her arm around his neck.” That night, claims the source, they stayed up quite late.

I’m sure the two of them were having a perfectly harmless conversation about Sean’s next Oscar-caliber movie he plans to direct. Nothing to worry about. It’s actually a documentary entitled Sean Penn Does a British Chick. Wait…

Photos: Splash News