A man who had his girlfriend unknowingly participate in a cheating-themed show broke down into tears when he watched her flirting with a hunky guy.

The man reached out to the YouTube show To Catch A Cheater, which aims to catch adulterous partners in the act while broadcasting their significant other's reactions on the internet.

He started by complaining that his girlfriend had stopped giving him oral sex, and lamented that her feminism had been intensifying as of late, which was apparently a significant issue for him.

What did you think would happen? A man who had his girlfriend unknowingly participate in a cheating-themed show broke down into tears when he watched her flirting with a hunky guy

It begins: At the beginning of the set up, the unassuming girlfriend sat outside a coffee shop to work on a women's studies paper, when a stranger asked if he could sit with her

'She started to do all this feminist s**t,' he told the host of the program. 'Like, cut off her hair. Like, she just stopped shaving.'

The man then added that he was looking to propose to his girlfriend, whom he called his 'soulmate'. Yet, he admitted he had 'no f*****g idea' how long the woman had been interested in feminism, even though the movement is apparently extremely important to her.

At the beginning of the set up, the unassuming girlfriend sat outside a coffee shop to work on a women's studies paper and enjoy an iced coffee.

An unknown man appeared as part of the experiment and asked if he could sit next to her.

The girlfriend let him use the chair next to her, and the charming stranger promptly began flirting with her, asking whether she was a model, and claiming he was a Harvard Law School graduate who had just started a new firm and worked on sexual harassment cases.

'How do you feel about the whole debacle with Harvey Weinstein?' the girlfriend asked.

Sure: The charming stranger promptly began flirting with the girlfriend, claiming he was a Harvard Law School graduate who had just started a new firm

Moves: After a bit of chit chat, the new man showed off his muscles, then offered to work out with the girlfriend, or to take her out for drinks

Offering his hot take, the man called Weinstein, who has been accused of sexual harassment by 60 women, and, in some cases, of rape, 'not a good guy'.

Meanwhile, the original boyfriend kept wincing at the interaction, apparently horrified to see his partner converse with another person.

The girlfriend did clarify that she had a partner, but said they were in an 'open relationship', which appeared to shock her boyfriend even more.

After a bit of chit chat, the new man showed off his muscles, then offered to work out with the girlfriend, or to take her out for drinks. He asked for her number, which she agreed to give him.

At this point, the boyfriend, behind his screen, started venting about his partner being a 'f*****g feminist', which according to him, is incompatible with giving people her number.

The conversation took an even stranger turn when a woman stopped by in her car and said the man hitting on the girlfriend as part of the experiment had a girlfriend of his own.

Not liking what he's seeing: The boyfriend, who was watching the experiment unfold, broke down at one point and started shedding tears

Bursting his bubble: 'I just can't f*****g believe it, man,' the dismayed boyfriend told the host, adding: 'She's like a totally different person, man'

Not playing: The boyfriend then decided he no longer wanted to be filmed as part of the program as he kept expressing his sorrow

At that, the show's host said that person was a 'random lady' who was apparently not supposed to intervene.

The boyfriend, who was still watching the experiment unfold, broke down at this point and started shedding tears.

'I just can't f*****g believe it, man,' he told the host, adding: 'She's like a totally different person, man.'

He claimed his girlfriend shouldn't have 'let' the other man sit down and talk to her, and chose to bring up his partner's sexuality by telling the host: 'She told me she was a f*****g virgin when I met her.'

The boyfriend then decided he no longer wanted to be filmed as part of the program as he kept expressing his dismay.

He ultimately decided to confront his girlfriend by showing her the footage. While he did bring her to the host's home to do so, the episode ended before viewers could see her reaction.