After the Feb. 5 announcement that Hollywood golden couple Tom Cruise, 38, and Nicole Kidman, 33 have separated, an even more shocking revelation has surfaced: Cruise filed for divorce on Wednesday in a Los Angeles Superior Court, stating in his claim that couple has actually been separated since December 2000. PEOPLE reports in its latest cover story that the dissolution of the seemingly happy pair's marriage has surprised even those closest to them. Kidman's mother, Janelle, a nurse educator, told PEOPLE, "We are all very upset" by the announcement. PEOPLE also reveals that the demands of their successful careers put a serious strain on the 9-year, 11-month marriage (they married in December 1990 after meeting on the set of "Days of Thunder"). One of those difficulties might have been Kidman's strong ties to her native Australia, where the couple has a home (they also own an estate in Los Angeles). Kidman's friend John Duigan told PEOPLE that adapting to each other's cultures -- and countries -- "may have ultimately contributed to their parting of ways." Rumors that Cruise's devotion to Scientology helped destroy the marriage -- with hints that Kidman might have had reservations about raising their children, Isabella, 8, and Connor, 6, in the faith -- are quashed by those close to them. "Scientology had nothing to do with this," the couple's spokesperson Pat Kingsley said. "They are not being controlled. They are not being counseled." What is clear is that Cruise cited irreconcilable differences as the reason for requesting the divorce and is asking for joint custody of their children. Duigan also told PEOPLE that, eventually, "Nicole will probably live in Sydney," describing the relations between Cruise and Kidman as "30 percent friendly. They are being adult about it, for the children."