Gillian Anderson has split from her longtime partner Mark Griffiths. The duo, who never got married, share sons Oscar, five, and Felix, three and spent six years together. A representative for the actress told Us Weekly magazine: "Gillian Anderson and her partner Mark Griffiths have amicably separated after six years together." 'The X-Files' and 'House of Mirth' actress has been married twice before. She and film art director Clyde Kotz, with whom she shares daughter Piper, 17, divorced in 1997. The star and documentarian Julian Ozanne were married for two years before parting ways in 2006. Last month Gillian revealed...