A new book looking at the making of the popular sitcomThe Big Bang Theoryhas revealed some endearing details about the behind-the-scenes romance between the series starsKaley CuocoandJohnny Galecki. In an excerpt published byVanity Fair, the details of the off-screen romance are shared in quotes from both stars, who dated for two years in 2008. The conversation reads:

CUOCO: “I had a very big crush on Johnny early on. I was so not even hiding it. He has such swagger. We were both dating people at the time, but I only had eyes for Johnny. Then, when I found out he had eyes for me too, I was like, Uh‑oh, this is going to be trouble.”

Kaley Cuoco Looks Back at The Big Bang Theory Finale One Year Later

GALECKI: “I have a healthy ego, but you really have to kind of club me over the head to let me know you’re flirting with me. I had zero idea of any sort of crush before Kaley and I began dating.”

CUOCO: “All the scenes up until we actually got together in real life, it was obvious there was always something there. There was chemistry and we were crushing on each other. That was the whole first season until we actually got together for real.”

Related:The Big Bang Theory: Where the Cast is Today

The Big Bang Theory’sHelped Push the Pair Into a Relationship

While it is clear from the words of both stars that there was an instant spark between them, they go on to explain how one certain moment inThe Big Bang Theoryhelped to provide a moment for them to take their relationship to the next level…literally. It was a dream sequence in an episode called “The Nerdvana Annihilation,” in which Cuoco’s Penny and Galecki’s Leonard had to get up close and personal in an elevator shaft. They said:

GALECKI: “We had to be in each other’s arms—and for quite some time, because it was a bit of a stunt that we were doing. It was a whole thing, and it was a pretape since it took a little while. Kaley didn’t look freaked out at all. In fact, she looked extremely happy in those arms. That was certainly one of the moments that I think—”

CUOCO: “I think we fell a little in love in that elevator shaft.”

GALECKI: “We felt something, yeah. I think that was a massive turning point [in our relationship]. At that point, both she and I knew that something mutual was felt, and that it was going to be more of a distraction from the work to try and continue to ignore it than to actually recognize it and surrender to it.”

Of course, both stars have moved on since dating, both from each other and from the show, withCuoco having recently appeared in HBO’sThe Flight Attendant, while Galecki reprised hisRoseannerole of David Healy inThe Conners. The pair did briefly appear on screen again when Galecki made a cameo appearance in an episode ofLip Sync Battlethat Cuoco was performing in.