Kevin's rep tells TMZ, "It is with great sadness that circumstances beyond his control have transpired which have resulted in Mr. Costner having to participate in a dissolution of marriage action." The rep went on ... "We ask that his, Christine's and their children's privacy be respected as they navigate this difficult time."
Christine is not asking for spousal support. Kevin's response, filed by disso-queen Laura Wasser, says "Spousal support to be payable to petitioner pursuant to the terms of the parties' Premarital Agreement." In other words, there's a prenup.