The 71-year-old actor, who died on Monday (5 December) after a short illness, starred with Travolta in the 1989 film Look Who’s Talking.
In the film, Alley and Travolta play love interests James and Mollie Ubriacco, who meet by accident when Mollie jumps into a taxi after going into labour.
During a 2018 appearance on Celebrity Big Brother UK, Alley said that she “loves” Travolta.
“I did love him; I still love him,” she said at the time. “If I hadn’t been married, I would’ve gone and married him and I would’ve been in an airplane because he has his own plane.
In 2013, the late actor also told Howard Stern that what she felt for Travolta was special and that the feelings between the two were allegedly mutual.
“It took me years to not look at John as a romantic interest,” she said, adding that he was “the greatest love of my life”.
During this time, Alley was married to Parker Stevenson, while Travolta was with Kelly Preston.
In another interview in the same year, Alley told Dan Wooton that not being romantically involved with Travolta was “one of the hardest things I’ve ever done”.
“[It was] the hardest decision I’ve ever made because I was madly in love with him – we were fun and funny together,” she said. “It wasn’t a sexual relationship because I’m not going to cheat on my husband.
“But, you know, I think there are things that are way worse than sexual relationships, than cheating on someone that way,” Alley added. “I consider what I did even worse because I actually let myself fall in love with him and stay in love with him for a long time.”
Alley also admitted that she kept on flirting with Travolta after his marriage to Preston until the moment she pointed it out.
“Kelly came up to me, and they were married then, and she said, ‘Erm, why are you flirting with my husband?’ “ Alley said. “And that was sort of when I had to make a decision and that was pretty much the end of that.”
The Cheers star was surrounded by loved ones at the Moffit Cancer Center in Florida in her final moments, according to her family.
Soon after her death, Travolta paid tribute to her on Instagram.
“Kirstie was one of the most special relationships I’ve ever had,” he wrote on Instagram. “I love you Kirstie. I know we will see each other again.”