The 61-year-old actor married Jolie, who is 20 years his junior, in 2000 after the two met on set of the 1999 movie, "Pushing Tin." They separated in June 2002 and divorced the following year.
"I never felt good enough for her," Thornton tells November issue of GQ magazine. The Oscar winner says Jolie's high-profile life wasn't his speed, and that he's "real uncomfortable around rich and important people."
That being said, Thornton adds that he's still friends with his ex-wife and speaks to her every few months.
In 2014, the actor told The Hollywood Reporter that he was "not fond" of that "crazy time" when he was married to Jolie, which included wearing vials of each other's blood around their necks. "Vial of blood is very simple," he explained. "You know those lockets you buy that are clear and you put a picture of your grannie in and wear it around your neck? She bought two of those. We were apart a lot because she's off making Tomb Raider and I'm making Monster's Ball. She thought it would be interesting and romantic if we took a little razor blade and sliced our fingers, smeared a little blood on these lockets and you wear it around your neck just like you wear your son or daughter's baby hair in one. Same thing."
After her split with Thornton, Jolie struck up a relationship with Pitt after meeting him on set of their 2005 film, "Mr. & Mrs. Smith." In September of this year, Jolie filed for divorce from Pitt after two years of marriage and 11 years together. Just this week, the 52-year-old actor was cleared of child abuse allegations by Department of Child and Family Services.
In a statement to ET, Jolie's rep said the mother of six was "relieved" that the investigation had concluded, and that her focus has always been the health of the family.