According to People.com, Thurman split from the multimillionaire on Nov. 15.
The couple began dating in the summer of 2007.
A source says, "The engagement ended awhile back... They remain friends... She will probably give (the ring) back. She wants to return everything that is his."
Thurman, 39, admitted in September that she wasn't planning to marry London-based Busson anytime soon. She told W magazine: "I'm happily engaged but we haven’t set a wedding up. I'm not in a rush to do anything. One day we'll do it, when we're ready. We can't live anywhere else because my children's father lives here. We'll figure it out."
A spokesperson for the actress has declined to comment.
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