John Travolta is mourning the loss of his "Grease" co-star Olivia Newton-John, who died Monday at the age of 73.
"My dearest Olivia, you made all of our lives so much better. Your impact was incredible," he wrote on Instagram alongside an old photo of Newton-John. "I love you so much."
The two starred in the iconic 1978 movie musical as Sandy and Danny, cementing themselves as one of Hollywood's most beloved onscreen couples.
"We will see you down the road and we will all be together again," Travolta, 68, continued. "Yours from the first moment I saw you and forever! Your Danny, your John!"
Newton-John's death was announced via a statement from her husband, John Easterling, and shared to her verified social media pages. In it, Easterling noted that Newton-John "passed away peacefully" at her ranch in southern California surrounded by family and friends.
"Olivia has been a symbol of triumphs and hope for over 30 years sharing her journey with breast cancer," Easterling said in the statement, pointing to the work she did through her Olivia Newton-John Foundation, after first being diagnosed in the early '90s.
The actress and singer battled a recurrence of breast cancer in 2013, and again in 2017, which metastasized to the sacrum and progressed to stage 4.
In addition to her husband, Newton-John is survived by her daughter, Chloe Lattanzi. Lattanzi, 36, reacted to her mother's death on Instagram by sharing a slideshow of photos of the two together throughout the years.