Jessica Turns to Self-Help Book

NICK Lachey and Jessica Simpson may have just had a "romantic" Italian vacation on OK! magazine owner Richard Desmond's dime, but they continue to lead separate lives. Upon their return last Friday, Lachey ditched Simpson to party in Las Vegas, and "Jackass" star Bam Margera — who had a fling with Simpson earlier this year — confirmed to Us Weekly that she had left Lachey. More evidence the two have split? Simpson, who now lives with her assistant Cacee Cobb, is spending her third wedding anniversary alone, in Africa. Sources tell PAGE SIX that Simpson, her dad, Joe, and Cobb will travel to Nairobi for Operation Smile — her pet charity that fixes cleft lips — for 10 days. The trio will have a safari elsewhere in Kenya — all without Lachey. A rep for Simpson says: "Operation Smile is an organization that is very special to Jessica, and she is looking forward to participating in more missions. Nick will be unable to join Jessica on the next trip because of work commitments in Los Angeles."