Causing quite a stir with his Independence Day sweat session, Sean Penn and his rumored new girlfriend were spotted on a run together in Malibu, California yesterday (July 4).

The 50-year-old actor, who split from 26-year-old Scarlett Johansson last month, has seemingly moved on to a new leading lady - brunette stunner, Stacey Koplin.

Now that Scarlett Johansson and Sean Penn's "are-they-or-aren't-they" relationship is officially no more, the reasons behind the unlikely couple's split have finally been revealed.

According to an Us Weekly insider, the 50-year-old actor broke it off with his much younger girlfriend because he simply isn't interested in getting serious right now.

Carrying on the tradition of showcasing great flicks, the 64th Cannes Film Festival premiered “This Must Be the Place” earlier today (May 20).

Sean Penn and Eve Hewson showed up at the Palais des Festivals to promote their new movie, both dressed snazzy for the event.