Kaley Cuoco and Johnny Galecki share how they fell in love while making 'The Big Bang Theory,' from flirty texts to a sexy cat costume

Kaley Cuoco and Johnny Galecki share how they fell in love while making 'The Big Bang Theory,' from flirty texts to a sexy cat costume
Kaley Cuoco holding Johnny Galecki's hand
Kaley Cuoco as Penny and Johnny Galecki as Leonard in "The Big Bang Theory."CBS

Kaley Cuoco admits she had a "big crush" on Galecki right when they started working on the show. He says he had "zero idea."

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"The Big Bang Theory."CBS

According to the oral-history book "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series," Cuoco was instantly drawn to Galecki.

"I had a very big crush on Johnny early on," Cuoco says in the book. "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.'"

Galecki says in the book: "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."

Things changed when they had their first kiss, during the sixth episode of the first season, when Penny dresses as a sexy cat.

Kaley Cuoco as a sexy cat and Johnny Galecki as Lord of the Rings character
"The Middle Earth Paradigm" episode in season one.CBS

"I knew I looked real cute in that outfit, so I was feeling really good about myself," Cuoco says. "And I knew he thought I looked cute because he commented on how cute I looked in that outfit earlier. But I was definitely nervous before that kiss."

Galecki adds: "I mean, Kaley Cuoco as a kitty cat? Come on!"

Galecki says he began to have feelings for Cuoco when they did this elevator-shaft dream sequence later in season one.

Johnny Galecki kissing Kaley Cuoco in elevator shaft
"The Nerdvana Annihilation" episode in season one of "The Big Bang Theory."CBS

In the dream sequence, Leonard saves Penny in the elevator shaft and they kiss. In reality, they were nose to nose for hours shooting the sequence. It was there when Galecki began to feel what Cuoco was already feeling.

"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," Galecki says. "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 — "

"I think we fell a little in love in that elevator shaft," Cuoco adds.

"We felt something, yeah," Galecki says. "I think that was a massive turning point. 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."

The cast hung out before season two began, and Galecki ignored Cuoco's flirting.

kaley cuoco and johnny galecki big bang theory
Cuoco and Galecki.Rich Polk/Getty Images

Cuoco had just broken up with her boyfriend when Galecki invited her to the seaside town of Montecito, California, to hang out with the cast. She admits she tried to get Galecki to come to her room the first night, but he declined.

"I went down to the front desk and got her a cabin, which ended up being the cabin next to mine," Galecki says. "By the time she showed up it was pretty late, and I had gone to bed. And then I got a call. It was Kaley. She said, 'There's a bug in my room.' I was like, 'Yeah, probably. You're in a cabin.' She said, 'You have to come and kill it.' I said, 'I'm not doing that.' Now, still to this day, I don't know if this story is bullshit or not, and if she was flirting with me because she had just broken up with her boyfriend, but I did not go over to her cabin."

"There was definitely a bug in my room and I was flirting with him!" Cuoco said. "So both were true! I was like, 'Ooh, this could be a good way to get him in there!' But that didn't work. I couldn't believe he turned me down. I still think he turned me down because he knew what I was doing."

Galecki finally made his move after a rehearsal day during season two. It led to "kissing in the parking lot," Cuoco says.

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"The Big Bang Theory."Sonja Flemming/CBS

"I had gone over to the Smoke House Restaurant in Burbank after rehearsal," he says. "I was there for a bit when I texted Kaley because I knew she lived in the valley. I said, 'Hey, I'm just having a glass of white wine. Are you nearby?' And she texted back yes and was there in like twenty minutes or something. She later told me she was like forty-five minutes away when she got that text."

"I was so excited when he texted me," Cuoco adds. "And I knew that was going to be trouble — getting a glass of wine with him. I knew. And we kissed at the bar! It's so dark in there that you almost feel like you can do anything, but then it was like, 'Uh‑oh, I think this is really going to be bad.'"

She says: "We started kissing in the bar area, and then we were kissing in the parking lot. Johnny can get really in his head and want to hide, whereas I'm the direct opposite.

"I would have told everybody the next day at the table read. I would have announced it and said, 'We're together!' But he was like, 'We can't tell anyone!'

"So we kept it quiet. And don't forget, it was different then. Social media was nowhere what it is now, so it was easier to keep it hidden. You didn't know as much about people as you do now. It's a different world."

Galecki says they went back to Cuoco's place, where she disappeared for a moment and returned "wearing nothing but a towel, and sat on my lap." Cuoco disputes his account.

Kaley Cuoco Johnny Galecki
Cuoco and Galecki.Alberto E. Rodriguez/Getty Images

"After that kiss at the Smoke House, she said, 'You gotta come over to my house,' so I did," Galecki says. "And then she disappeared. She came back having showered, wearing nothing but a towel, and sat on my lap. I was like, 'Okay, I guess we're dating!'"

"I remember being in a robe and fully clothed underneath!" Cuoco says. "We obviously remember things quite differently, but I love this story."

"I promise that my version is correct," Galecki adds. "I'm only kissing and telling because Kaley loves this story."

Both say they never hooked up while on set.

Kaley Cuoco Big Bang Theory
"The Big Bang Theory."CBS

"Johnny was very worried about ruining the fans' outlook on Leonard and Penny, because they weren't even dating yet at that point in the series," Cuoco says. "He was so cerebral, and I'm like, 'What?! Who fuckin' cares?! They're gonna be fine!'"

"And if we broke up, how would that affect their acceptance of the characters?" Galecki adds. "I didn't like the idea of people feeling like, 'Oh, Joanie and Chachi really do love each other!' At that point in my life, that felt embarrassing. I would feel differently about it today."

After nearly two years together, they broke up. Cuoco says they "ran out of things to talk about."

Johnny Galecki Kaley Cuoco
Galecki and Cuoco.Kevin Mazur/WireImage

"We're from very different worlds, but we also seem to melt into each other's worlds in certain ways," Galecki says. "It was a lot of fun to teach one another different things, but then when I came to wanting different things, that made things more complicated."

He adds: "I think one of the things that created a chasm between us was my strict policies of privacy, and Kaley being very, very open about her life. I was very uncomfortable with being public about it, and I think that hurt Kaley's feelings a little bit, and I can understand that.

"It certainly wasn't because I was embarrassed of her or our relationship, but I wanted to be protective of the audience's acceptance of Penny and Leonard, and without distraction from the tabloids."

"Johnny and I also ran out of things to talk about, because we'd be at work all day," Cuoco says. "We had no mystery. But we were together for a long time. We really adored each other, and we were lucky because as our breakup was happening, there was no foul play, there was nothing bad about our relationship ... it just ended."

On the show, Penny and Leonard eventually get married — twice. Both actors say those scenes weren't weird.

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Penny and Leonard get married.Sonja Flemming/CBS

"You would think it might have been weird given there was a time Kaley and I did consider marrying, so those scenes would have been complicated at the very least," Galecki says. "But she and I are seasoned professionals, and we've been doing this since we were kids, so we used it as a bit of therapy."

"Johnny and I got so close through the show and our experiences," Cuoco says. "There was such a comfort level, and he always was so supportive of me. We had a lot of talks where I'd be like, 'I don't know about this,' and then we'd go outside and have a chat. Whatever I needed.

"We would almost finish each other's sentences. We knew each other's characters so well, but he was just constantly a steadfast person in my life, on that show, on that set."

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