Kaley Cuoco had to film sex scenes with her ex on The Big Bang Theory

Kaley Cuoco has opened up about filming sex scenes with her The Big Bang Theory co-star Johnny Galecki after their break-up.

Fans of the sci-fi sitcom will be aware that Cuoco and Galecki's on-screen counterparts Leonard and Penny would end up getting together before tying the knot in later seasons. But did you know the actors were once an item in real life?

Romance would blossom between Cuoco and Galecki after they met on-set during the early days of the season, with the actors embarking on a relationship in 2008.

But while Penny and Leonard went on to announce they were expecting a baby in the series finale, the romance between the two actors would ultimately fizzle out two years later.

Thankfully, the pair remained on friendly terms after their break-up. However, it did lead to some awkward moments on set as things between their characters heated up.

Leonard and Penny were the major love story of the series (CBS)

During an interview with Dax Shepard on The Armchair Expert podcast back in 2020, Cuoco opened up on what it was like to film sex scenes with her ex.

"When we broke up, obviously it was a little sensitive for a minute, but I remember those weeks that Chuck had written these episodes where all of a sudden our characters were like sleeping together every other second," the actress recalled.

Fortunately both Cuoco and Galecki were able to take the predicament in their stride, however The Flight Attendant star did wonder about the unfortunate timing of their on-screen relationship.

"Johnny and I talk about it and I think [Chuck] did that on purpose — just to f*** with us.

"If I was with [Lorre now], I would ask him, because that came out of nowhere. All of a sudden these characters were all up on each other," she added, laughing.

Cuoco also reflected on their short-lived romance more broadly, saying: "We dated really early on for almost two years. When we did the pilot, I was crushing so hard on Galecki, but he had a girlfriend.

"We got together and just fell mad for each other for two years, but then we broke up," she continued.

Cuoco has since found love with actor Tom Pelphrey (Mike Tran/Variety via Getty Images)

"Luckily, Johnny and I came out of it so brilliantly and we're closer today than we ever were."

Cuoco may have not had her 'happy ever after' with Galecki, but that doesn't mean the actress has been unlucky in love. The Based on a True Story star has been in a relationship with Tom Pelphrey since 2022.

The couple welcomed their first child, a daughter, in March 2023, before getting engaged on 14 August, 2024.