In 1998 Haddon started dating actor Christian Slater. The couple married on 12 February 2000, and have two children, Jaden Christopher (born 6 April 1999) and Eliana Sophia (born 15 August 2001). They announced their separation over Christmas 2004, while Slater was performing in a stage play of "One Flew Over the Cuckoo's Nest in London's West End. They officially separated in 2005 and divorced in November 2007.