Hawke, now 42, was 27 when he wed 'Kill Bill' star in 1998.
The actor said he thought marriage would bring stability in his life, Elle magazine reported.
"Success when you're young is really overwhelming. The world felt out of control. And I wanted to stop it from spinning so fast. I thought marriage would decrease my variables or something. I was absolutely wrong," Hawke said in an interview to the magazine.
The former couple raise two children together --daughter Maya, 14, and son Levon, 10. Hawke feels he was too immature to take on a thing like marriage.
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Hawke and Thurman were married for five years before separating in 2003. Two years later, in August 2005, they finalized their divorce.
Hawke remarried with Ryan in 2008 and they have two young daughters, Clementine and Indiana.
Thurman, who was married to Gary Oldman for two years before meeting Hawke, is engaged to French financier Arpad Busson and has a daughter with him.