A shocked Holly Willoughby immediately apologised after her sudden outburst during a This Morning phone-in.
One person called into the show and explained how her ex-boyfriend tried to get in touch with her to reunite even though he has a partner.
The woman called in to seek advice from agony aunt Vanessa Feltz on the topic of ex-partners.
She told Vanessa and hosts Holly and Phillip Schofield: "So I split up with my boyfriend about eight years ago. During lockdown, he contacted my family and he asked to speak to me.
"We had a bit of a catch-up and he admitted he still has feelings for me. I'm now openly gay, which he knows about."
She continued: "I've not heard from him for about a year or so and I received a message from him a few weeks ago to say he'd met up with my parents and asked if I wanted to catch up as well.
"I confronted my mum about this - she didn't think she'd done anything wrong. She wants us to be friends, she's still very fond of him, and I feel quite betrayed that she did that."
Phillip then asked the caller if she has a partner, to which she answered: "No I'm still single but he does have a partner."
At this point, Holly gasped out a 'Jesus' before quickly saying: "Sorry, sorry, sorry. I didn't expect it."
Phillip seemed amused by her outburst and Holly continued: "If that was my daughter - say this was Belle in this situation, and some guy was coming who had a partner.
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"I'd be like what a treacherous little so-and-so, cheating on his partner and coming round here."
Hilarious outbursts are usually more common from Phillip, but it looked like he loved every moment of Holly's shock.
Just yesterday, Holly jumped to Kim Kardashian's defence after she wore Marilyn Monroe’s iconic bejewelled dress to the Met Gala.
This comes after a Marilyn Monroe collector claimed that “permanent damage” has been done to the iconic Monroe wore to serenade John F Kennedy on his 45th birthday.
Holly told ITV viewers: " Kim Kardashian has been criticised for causing permanent damage to the dress.”
She then added: "We should point out she literally wore it from one red carpet to the other, at which point got changed and wore a replica, which she partied the night away in.
"So it seems like they were careful."
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