7. Sienna Miller
Cheater: Balthazar Getty
Date Of Affair: May 2008 - May 2009
There's love triangles then there's love hexagons, which might describe this next entry. In 2006, ravishing actress Sienna Miller broke up with actor Jude Law (who she started dating while he was still married) after he admitted that he had cheated with his children's nanny. Miller then had a brief encounter in '07 with Matthew Rhys of the television series Brothers & Sisters before breaking things off to start a relationship with Balthazar Getty, Rhys TV co-star and the guy who introduced Getty to Miller. You still with us? Good because we left out that Miller also went out with a dude name Rhys Ifans right after Matthew Rhys, but then that really would have been confusing. Anyways, the fetching blonde Brit really caused waves with her relationship with Balthazar considering he was recently separated from his wife Rosetta shortly after she had given birth to the couple's fourth kid. Those tidal waves turned into a monsoon when the sexy siren Sienna was photographed topless kissing Getty aboard a boat off the Amalfi coast in Italy. The free spirited star of GI Joe: The Rise Of Cobra got a rise out of not only Balthazar but the public, who really weren't all that pleased with her actions. Miller later remarked that she had a "semi-breakdown" because of the uproar. After about a year together, the exhibitionist pair split up, Sienna going back to Law and Getty going back to his better half.