While this isn’t the Yellowstone star’s first divorce, which cost the actor US$80 million (NZ$127m) and his reputation amid serial cheating rumours, Page Six revealed that one of Costner’s longtime friends defiantly defended the star, saying: “There was no issue of cheating at all.”
The couple were last seen publicly together at the Oscars last year, with many saying the pair looked happy at the event. A friend added: “Kevin was very surprised by Christine’s actions, he obviously doesn’t want the divorce and he would take her back. It’s disappointing, he loves her and he loves his children.”
Costner and Baumgartner have sons Cayden, 15; Hayes, 14; and daughter Grace, 12 - with the former couple both requesting joint custody.
Costner is infamous for being romantically linked to supermodels and Hollywood stars over the years, from Elle Macpherson to Halle Berry.
The Bodyguard actor has spent the past few months filming his television show Yellowstone in Montana, which may have led to increased pressure on his relationship with Baumgartner.
Costner once said: “The temptations are pretty strong and there’s a hungry world out there waiting for you to fall. So you can’t even dabble without paying a huge price.
“I try to conduct my life with a certain amount of dignity and discretion but marriage is a hard, hard gig.”
However, Costner’s representative told Page Six that any cheating accusations against the star are “absolutely not true”.
When asked why Baumgartner was leaving the actor, he responded: “I have no idea if Kevin even knows what the reasons are.”
A Yellowstone production source also was shocked by the divorce, saying: “No one knew about any issues. He was not ‘sequestered’ on the set and would often go home to visit his family.”
Baumgartner, a handbag designer, filed for divorce from Costner on Monday as a result of “irreconcilable differences”.
In the filing, Baumgartner asked for joint custody of the couple’s three children.
She did not ask for spousal financial support, however there is reportedly a prenup in place to protect Costner’s estimated US$250m (NZ$397m) fortune.
A representative for Costner, who declined to talk about the financial arrangements between the two, said: “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.
“We ask that his, Christine’s and their children’s privacy be respected as they navigate this difficult time.”