Credit: Michael Rozman/Warner Bros.

According to Carrie Fisher, no one knew she and Harrison Ford were having an affair on the set of Star Wars.

Speaking to Ellen DeGeneres for Tuesday’s episode of The Ellen DeGeneres Show, the Princess Leia actress and author explained how she kept the secret of their on-set tryst for 40 years. “I told other stuff to distract people so they wouldn’t figure it out. No one thought it was happening at the time — I don’t even know if he did,” she joked. “No, he did.”

Asked if she and Ford were in love, Fisher said, “Well it depends on who you ask. I was infatuation, probably. Love is more mature.”

As Fisher told DeGeneres, the relationship began, in part, because of “location.”

“That’s because everybody was away from home, so then the rules — I didn’t know this. I was 19. No one told me about location rules, or lack of rules,” she said. “But you can do whatever you want, as long as you film the movie. They can sleep together if their family’s not around.”

In her memoir The Princess Diarist, Fisher revealed her affair with Ford for the first time. “It was so intense,” Fisher told PEOPLE. Fisher was 19 at the time of the affair; Ford was 33 and married.