Official word of the split comes amid weeks of reports claiming Theroux is romantically involved with his "Wanderlust" co-star Jennifer Aniston.
"Heidi is heartbroken. She was completely blindsided. She and Justin had been together for years, they had a home. Then he met Jennifer and everything changed. At first he claimed he and Jen were friends," one insider told the New York Post.
However, another source insisted, "Things were already over between him and Heidi before he got close to Jen."
"Heidi and Justin have been together for 14 years," Bivens' publicist told the Post. "They met when she was 20 years old and he 24, and yes, she just moved out of their home last weekend. She has no comment."
Aniston's ex-husband, actor Brad Pitt, famously divorced her after working with Angelina Jolie on the 2005 film "Mr. & Mrs. Smith." They now have six children together.