Did Sienna Miller Put the Kibosh on Sean Penn’s Marriage?

Sienna Miller sure has a penchant for partying with guys who are with other women. The actress is a big fan of the “we’re just friends” excuse, to explain late-night, touchy-feely nights out with her guy pals. Most recently, her behavior with Sean Penn before his split from his wife, Robin Wright Penn, is coming into question.

Sienna and Sean were reportedly enjoying a soiree together at hotel suite in New York, recalls a source, who claims the British actress was positioned on Sean’s lap. “She was dressed very sexily. She had her arm around his neck.” A friend of Sean’s, however, explains that Sienna is simply affectionate and she “drapes herself over people she likes.” OK, maybe I’m just being old-school here, but Sienna does not need to be “draping herself” over other people’s husbands. She is not a throw blanket. Yet.

Photos: Splash