Olivia Newton-John passed away on August 8 after a lengthy battle with breast cancer.

However, it has been found that she carried one secret with her to the grave.

According to Globe magazine, the former "Grease" star was secretly in love with her co-star John Travolta.

Sources revealed that Olivia and John have the same romantic feelings for each other in real life. However, timing was never on their side.

They stated that John was still hurting from the death of his fiancée, Diana Hyland, who died in his arms three months earlier from breast cancer, when he stepped into his character as Danny Zuko and Olivia became Sandy Olsson for the 1978 film musical.

According to an informant, Olivia assisted John with his sadness, and the actor returned the favor when the former was stricken with breast cancer in 1992 and again in 2013.

The "Hairspray" star apparently stayed by Olivia's side even after she was diagnosed with stage 4 cancer in 2017.

The "From Paris With Love" actor was also there for the "Two of a Kind" actress when her 11-year marriage to Matt Lattanzi ended in 1995.

John was already married to Kelly Preston at the time. Unfortunately, Kelly and John's 28-year love story came to an end in 2020 when she died due to breast cancer.

"Olivia and John's shared traumas," according to the source, "They kept them as close as two individuals could be - without being lovers!"

Olivia, according to close confidantes, even offered John her support when Kelly died. Olivia was already married to John Easterling at the time.

"Fate brutally separated them," the insider stated.

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When Olivia Newton-death John's was announced, John Travolta paid her a heartfelt tribute online.

He promised to meet her "down the road," and said that they would be together again.

"Yours forever from the moment I saw you," John said.

It's unknown whether they covertly dated off-screen, but they were only a relationship when they appeared together on the big screen.

According to John Travolta, despite having real-life chemistry, their relationship was strictly platonic.

Meanwhile, this allegation should be taken with a grain of salt because there is no proof that Olivia Newton-John was secretly in love with John Travolta.

Olivia even said in an interview with "No Filter" podcast in 2018, the reason why she couldn't date John while filming really helped their chemistry on screen.

"It might have been a real disaster had we decided to date or we had a falling out or something."

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