'Friends': The One With the Truth about Ross and Rachel

After 10 years on the air and 17 years since the final episode, 'Friends' still has its secrets, and one of the biggest was revealed on Thursday in a reunion special airing on HBO Max.

The on-again, off-again romance between characters Ross Geller and Rachel Green wasn't just for the cameras.

Actors David Schwimmer and Jennifer Aniston revealed for the first time that they had major crushes on each other in the early years of the series.

They said the mutual attraction lasted for the first two years of the show, but they never got together as a couple off-screen because they were both in relationships or between relationships with other people.

"We were both crushing hard on each other, but it was like two ships passing because one of us was always in a relationship. So we never crossed that boundary, you know. We respected that," said Schwimmer.

He recalled that "in the very first year or two when we had breaks from rehearsal, there were moments when we would cuddle on the couch."

"How did not everyone know we were crushing on each other?" he asked co-stars Matt LeBlanc, Matthew Perry, Courteney Cox and Lisa Kudrow.

"We knew, for sure," said Cox.

Friends: The Reunion comes 17 years after the comedy about 20-somethings living in New York City ended its 10-year run. It remains one of the most popular shows in re-runs and on streaming platforms.