Olivia Newton-John and John Travolta had ‘undeniable attraction’

They were the subject of persistent romance rumors after they steamed up screens in 1978’s “Grease.”

But Olivia Newton-John and John Travolta never got physical while filming the movie musical, and instead went on to share a 44-year friendship that remained strictly platonic.

In her 2018 autobiography “Don’t Stop Believin,’ “ Newton-John — who died Monday following a long battle with cancer — revealed the reason she never hooked up with her hunky co-star, despite their “undeniable attraction” toward one another.

“Yes, we really liked each other and there was an attraction, but we would never date because we were both involved with other people at the time,” the bubbly blond divulged in the tome.

“Both of us have a loyalty streak that runs deep,” she added, insisting she would never cheat on a partner.

Still, the pair enjoyed a strong flirtation, with Newton-John going on to recall her amorous audition alongside Travolta.

“John came out to meet me. Our eyes met. When we walked inside the room together, it was magic, and everyone saw it,” she cooed. “They couldn’t deny this kind of chemistry.”

Their fondness for one another only intensified over the course of the two-month shoot, with the Australian beauty becoming enamored by her co-star’s kindness.

Newton-John divulged that Travolta purposely messed up a scene so that they could shoot it again because he believed that she could “do better.”

“He said: ‘Sorry I messed up. Liv, I did that on purpose because I don’t want them to use that take. I know you can do better,’ ” she recalled in the memoir. “I had great love and support from him and the feeling was mutual. I would be forever grateful for his concern.”

Newton-John also wrote about filming the final scene of “Grease,” where her character, Sandy, shows off her sexy makeover in leather pants and a tight tank top.

“There were gasps, catcalls and a lot of whistling,” she penned, before detailing Travolta’s reaction to her eye-catching ensemble.

“John was filming the song ‘Sandy’ and I strutted on set. He stopped singing mid-note, as his head jerked up and his eyes popped. ‘Tell me more, tell me more,’ he shouted. We laughed so hard. It was exactly the reaction I wanted,” Newton-John wistfully wrote.

Meanwhile, the superstar claimed that Travolta told her on set: “Liv, it’s every guy’s dream to have you as his girlfriend.”

In her book, Newton-John wrote that Travolta later told her: “It almost happened between us a few times, but it didn’t. Sometimes life just offers you the wrong timing. We had to leave it as dear friends.”

Indeed, the pair enjoyed a friendship for the ages, frequently appearing together on red carpets and reuniting for “Grease” anniversaries.

In 2018, Travolta told People magazine that the huge success of their flick had helped them stay connected.

“When you share that kind of meteoric success — and nothing has been able to exceed it— you share a bond,” he stated. “I’ve been through her having a child, getting divorced, losing her sister. She’s been through my getting married, having children. It’s wonderful and full of shared memories.”

Following Newton-John’s death, Travolta was the first A-lister to pay tribute to his beloved pal.

“My dearest Olivia,” he emotionally wrote on Instagram. “You made all of our lives so much better. Your impact was incredible. I love you so much.

“We will see you down the road and we will all be together again. Yours from the first moment I saw you and forever! Your Danny, your John.”