Giggling together at awards shows or lounging in the sunshine in Cabo over Thanksgiving, Jennifer Aniston and Chelsea Handler once seemed inseparable.

Aniston could vent to her laugh-a-minute bestie about her angst over Angelina Jolie, while they both lavished praise on each other in interviews, joking about their years-long friendship – until suddenly, without explanation, the lovefest was over.

Now, the Daily Mail has learned what really caused this friendship to cool. And, as is so often the case, it turns out that loose lips sank this ship.

‘Jen wants to be more private, while Chelsea wants to be front and center, so perhaps a breakdown was always inevitable,’ a source close to Aniston said.

The two women grew close after Aniston, 56, was a guest on Handler’s late-night talk show Chelsea Lately in 2009.

‘They jumped into their friendship headfirst and went from not knowing each other to being together 24/7,’ our insider spilled.

But the Daily Mail has been told that Handler always thought the two were much closer than they really were.

At the beginning, their friendship was based on a shared sense of humor. But when Handler, 50, started to publicly air private details about Aniston’s life, including hitting out at Jolie, 49, the Friends superstar was left reeling.

As everyone well knows, Aniston was involved in a years-long and headline-grabbing feud with Jolie who reportedly engaged in a scandalous affair with Brad Pitt while he was still married to Aniston.

The duo affectionately nicknamed ‘Brangelina’, met on the set of Mr. & Mrs. Smith in 2005, months before Pitt and Aniston divorced.

Jolie and Pitt then dated for years, welcoming six children together and eventually marrying in 2014, before their own acrimonious split just two years later.

That year, Handler started publicly ripping Jolie. At one point she even characterized the actress as ‘a f***ing lunatic’ who had driven her husband to booze and pot.

Handler said: ‘There are rumors that part of the problem was that Brad was allegedly drinking and smoking too much weed. I wonder why he would need to self-medicate.’

She went on: ‘Maybe because he could have been spending the last 12 years at Lake Como hanging out with George Clooney and Matt Damon, instead of being stuck in a house with 85 kids speaking 15 different languages. Oh yeah, because he married a f***ing lunatic, that’s why.’

Handler discussed Brangelina again in an interview with Grazia in 2016.

She defended her friend and said it was ‘ridiculous’ that people thought Aniston would care about her ex-husband’s romantic life.

‘It’s so stupid and pathetic,’ Handler said.

But the problem was, of course, that in speaking up so aggressively, Handler was essentially dragging Aniston into a drama she wanted no part in.

As our insider explains, what began as something ‘innocent’ started to seriously bother the Friends actress, who felt that – after a while – Handler was repeatedly bringing up Jolie seemingly for the sake of publicity.

It certainly didn’t help matters that, in 2015, Aniston had married her second husband, filmmaker Justin Theroux, who was said to dislike Handler.

One source said he thought she was ‘rude and obnoxious’ and that she encouraged Aniston ‘to act like she’s single.’

Ahead of Aniston and Theroux’s wedding, Handler had jokingly described her more-famous friend as a ‘burden’ because all anybody wanted to talk to her about was the impending nuptials.

Fast forward to 2017 when Aniston’s marriage to Theroux was breaking down and she once again became concerned that details of her private life would leak out.

‘Jennifer became paranoid, thinking that people around her were leaking stories to the press,’ our insider says. ‘Chelsea was still talking about Jennifer in interviews, and Jennifer automatically pointed the finger at her.’

By February 2019, when Aniston held a star-studded 50th birthday bash, rumors of a nasty rift abounded.

Handler, who nonetheless attended the birthday celebration, denied the gossip and tried to set the record straight on Australian talk show The Project.

‘Don’t believe any of it!’ she said. ‘We’re friends. Don’t worry… I love Jen.’

But it seemed to be too little to late for Aniston.

While our insider insisted that the pair do still talk – pointing out that Aniston is quick to like Handler’s Instagram posts – they admitted it is ‘not the same as it was, and it will never be.’

‘Chelsea seemed willing to do anything to be a star, and Jennifer was already a big name so of course there were hints of jealousy,’ our source added.

A separate insider said Aniston has ‘a wide group of friends which at one time included Chelsea, but she never made it into her inner circle like Courteney Cox or Jimmy Kimmel.’

Aniston often shares Instagram snaps with her 44 million followers featuring her close pals vacationing together or hanging out. Handler has yet to make an appearance.

Truth be told it seems unlikely she’ll be enjoying poolside cocktails with Aniston any time soon. Because, according to our sources, the women remain cordial but they’re never going to enjoy a ‘serious friendship’ again.