US Weekly first reported the happy news about the couple, who began dating in 2014.
"They both knew it would happen, but it wasn't a big thing to them because they were both in long marriages before," an insider revealed.
"There wasn't a rush."
Behind the scenes, Paltrow, 45, and 46-year-old Falchuk are already preparing for their pending nuptials — they've even sat for engagement photos, said the insider — but the Goop founder "is waiting to announce the news on her website."
Paltrow and former Glee producer Falchuk met when the actress made an appearance on his show as Holly Holliday, a substitute teacher.
"I think she just supports everything I do, thankfully," Falchuk once said
Paltrow was previously married to Coldplay singer Chris Martin for eleven years, while Falchuk's relationship with TV producer Suzanne Falchuk ended in divorce in 2013.
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