The couple is looking at dates in December after deciding where to exchange vows, dailymail.co.uk reported a source as saying.
The source explained that Theroux, 41, said it was a "breakthrough" as the "main source of uncertainty has been removed", adding: "Jen and Justin have gone back and forth on where to marry and whether to have a destination wedding so many times."
"Jen has always made it clear LA was her first choice and Justin has compromised and agreed to marry in California. Justin's reservations with LA are well known and he wanted to marry on the East Coast where his friends and much of his family is based, where he proposed to Jen and where he feels most comfortable," the source further added.
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