Mischa Barton has lashed out at Nicole Richie for severing their friendship, branding The Simple Life star "fickle". The OC beauty used to be spotted regularly at glamorous parties with the daughter of soul star Lionel Richie, but their relationship has gone cold after Richie stopped returning Barton's calls. Barton says, "I think of Nicole as a good friend but she hasn't been in touch recently. "It's quite fickle of her."