As her name again crops up in the news – this time over a Scotland Yard investigation into some $400,000 worth of missing Dior jewels after a British Elle photo shoot – Lindsay Lohan’s terminally on-again, off-again relationship with Samantha Ronson has now hit an ultimate dead end, a source close to the couple tells PEOPLE.

As it is, the two never officially got back together. And now, after Lohan’s most recent round of partying, they aren’t even friends.

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

Lohan’s antics included Twittering nude photos of herself to the press and long hours of partying in Los Angeles and New York.

“She is telling everyone that Sam dumped her again, but it makes no sense since they never got back together,” according to the source.

While the couple had been repeatedly photographed together recently, any reunion was strictly based on friendship, not romance, insists the source, explaining: “Sam is a nice person and wouldn’t throw anyone out of her life, but it was no more than that.”

Source