Heidi Bivens had dated Justin Theroux for 14 YEARS before he began seeing Jennifer Aniston recently, and only moved out of their place last weekend.
That's ... a long time. And a little surprising.
Bivens, 34, a costume designer, has moved out of the NYC home she shared for six years with Theroux, 39, her rep told the NY Post's Page Six:
"Heidi and Justin have been together for 14 years. They met when she was 20 and he 24, and yes, she just moved out of their home last weekend."
"She has no further comment."
An insider says he and Aniston, 42, "started hooking up on set" in Georgia last fall while shooting Wanderlust and while he was still with Bivens.
Hard to blame the guy. Have you seen those Jennifer Aniston topless ads for Smartwater? We're kidding ... although we're a little bit serious.
"But he had been trying to leave her for a while," the source said. "He broke it off for good in March," and they were "on an off for years."
"She doesn't want him to get frustrated with her usual covert way of doing things," a Theroux source said of Jen's new relationship attitude.
"So she's compromising and relaxing about the paparazzi."