Kevin Costner is desperately trying to save his marriage after his wife Christine Baumgartner filed for divorce last week.
The 68-year-old is said to have been "very surprised" by the split, with a friend saying Kevin seems unaware what the reasons are for their divorce.
There has been speculation that Christine gave Kevin an ultimatum before the breakup and is said to have urged him to quit Yellowstone to try and save their marriage.
A source has now said Kevin is trying to win Christine back.
"Everyone thought Kevin and his wife were super happy so it's all surprising. He truly loves her and is trying to get her back. He's been blindsided by this," a source said.
The former couple tied the knot in 2004 and they share three children together - Cayden, 16, Hayes, 14, and Grace, 12.
As news of their split broke, a second source told US Weekly that Kevin has been left "deeply saddened" by the divorce and is "trying to save his marriage".
The source continued: "Kevin loves his wife and children so this has been very hard on him. He is saying that this is his worst nightmare and he would do anything for his family."
After news of the divorce was made public, it was reported that Kevin's hectic work schedule ultimately led to tensions in the marriage.
A friend of Christine's said: "It's really knocked a hole in their family life.
"The show is such a mega-hit, producers want it to go on forever! However, Christine wants her husband to hang up his cowboy hat, with an insider saying her patience is starting to fray."
Speaking to Radaronline, they added: "She wants a firm commitment this is his last season — or he might have to hit the dusty trail!"
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