Stop us if you think you've heard this one before: Lindsay Lohan and Samantha Ronson are kaput. Again. E! News says the inconstant squeezes are on the outs for the second time in two months, with Sam, 31, supposedly snuffing out their flickering flame on Monday night via a "Mean Girls"-style text message.

"Go find someone else. You make me [bleeping] sick to my stomach," she allegedly wrote in the missive obtained by E!. "If you come anywhere near me or my house, I'll make you wish you hadn't. That's all I have to say. You're disgusting."

The venomous text reportedly came after a "nasty argument" (as if there's any other kind with these two).

Lindsay, 22, who just a few days ago was flashing a diamond ring following a London rendezvous with her capricious DJ inamorata of about two years, attempted to put a brave face on the drama.

"I love being alone. Feels safe coz I can only trust myself ... ya, sad," she wrote on Twitter on Wednesday. "But I'm cool with it."

It's already been a busy week for the starlet, what with being linked to an investigation involving a $400,000 jewelry heist, posting a topless picture on Twitter out of sheer boredom and allegedly acting "extremely oddly and erratically" at a New York City club.

And it's that behavior that People magazine says led to her latest estrangement from Ronson.

"Sam let Lindsay back into her life as a friend, but now even a friendship seems impossible," a source tells the mag. "No matter how many times she promises to change, Lindsay loses control and starts acting like a maniac."

What's more, the mole insists, their together-time in the wake of their very public bust-up in April, when Lohan cried she was "so alone" and "in absolute hell" in an Us Weekly cover story, wasn't romantic.

"She is telling everyone that Sam dumped her again," says the insider, "but it makes no sense since they never got back together ... Sam is a nice person and wouldn't throw anyone out of her life, but it was no more than [friendship]."

E! News also places some of the blame on Nicole Richie, Lindsay's former partner in cadaverous crime and currently a close pal of Ronson's.

A source tells E! that the expectant mom of 17-month-old Harlow is so over Lohan that she invited Ronson to a mutual pal's birthday shindig at the Bar Marmont in Los Angeles last week under strict orders to come without her sometime honey.

"Nicole refuses even to be in the same room as Lindsay," purports the snitch. "Sam went to the party, and it really upset Lindsay."

Lohan alluded to the snub last week, writing, "How can u invite one of a couple? Like, really? And at Chateau, really? Like again, really?"

According to E!, Ronson met up with Richie for dinner on Monday night and sent the supposed Dear Jane text shortly after.

If true, this would be the second time that Sam has seemingly let outside forces influence her decision to distance herself from Lindsay: Her family is said to have encouraged their April split.

But as a Lohan source wisely observed to People at the time, "It's a cycle that can go on forever."

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