The American Horror Story actress's publicist confirmed on Monday (December 19) that the two first decided to live apart two years ago and have since completely ended their romance, according to People.
Lange's representative declined to clarify the reason for the break-up, but an insider added: "They both are pursuing independent lives."
Acclaimed actor-playwright Shepard first began dating Lange in 1982. The couple have two grown children together.
Shephard was previously married to actress O-Lan Jones, with whom he had one son.
Lange also has a child from her relationship with Russian ballet dancer Mikhail Baryshnikov.
The actress has been nominated for a Golden Globe for her performance in American Horror Story, which wraps up its first season on Wednesday (December 21) at 10pm EST on FX.
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