Is JENNIFER ANISTON EVER going to marry Justin Theroux?

That’s what people are wondering after a shocking new twist developed in the seemingly endless saga of the celebrity couple’s engagement.

Brooding hunk Justin, 42, popped the question in August 2012 and talked about eloping. That never happened and nothing more has emerged other than vague plans with potential locations hopscotching around the globe from Greece to Paris to Hawaii to Mexico.

“Jen is the most  indecisive woman on the planet,” said a source. “She’s changed her mind a million times about everything.”

And now, sources say, the screen beauty, 45, has enraged her interminably jealous fiancé by flirting up a storm with Sam Worthington, the handsome actor who shot to fame in the sci-fi blockbuster “Avatar” and is now filming “Cake” in Los Angeles with Jennifer.

Sources reveal that their chemistry is white-hot on and off the set – and the rugged Australian has been meeting with Jennifer in private.

“Jennifer is insisting that she’s just good friends with Sam, but Justin is acting like a jealous teenager,” an insider told The ENQUIRER. “She’s told him to chill – and that Sam is deeply in love with his girlfriend (Australian model Lara Bingle) – but Justin keeps grilling her about Sam and it’s really getting on her nerves.”

It’s just one more bone of contention between the couple, who are tied to opposite coasts and consumed by their booming careers. While sources say Justin longs to settle in New York City, where he filmed his upcoming TV series “The Leftovers,” Jennifer wants to stay in her native L.A.

Meanwhile, the former “Friends” star is said to be gun-shy about her wedding to Justin being compared to her extravagant 2000 nuptials to ex-hubby Brad Pitt.

“Jennifer has been dreaming about a fairytale wedding to Justin,” said the source. “But it just keeps eluding her grasp.”