Kiefer Sutherland is back in the single game again. The “24” star has split with his long-term girlfriend of nearly three years, Allure magazine style director Siobhan Bonnouvrier, sources tell us. Sutherland, who was in town starring in Broadway’s “That Championship Season” until the end of May, has developed a friendship with wealthy New York mom Eleanor Propp, numerous sources say. Propp told us, “I am not dating Kiefer. We are just friends.” Sutherland’s rep didn’t get back to us.