After his girlfriend took him out to the street and began berating him, a crowd of onlookers gathered and started filming the scene, which has since been posted on YouTube.
The 20-year-old woman, named Cheng, was later arrested on suspicion of common assault, while the victim, 23-year-old Chui, was taken to hospital after an onlooker called the police.
She made him kneel on the pavement in full view of passers-by, and accused him of going behind her back by inviting in the other girl - who was standing next to the couple throughout the fight.
However, he insisted he had not asked the girl to come to his flat, saying: 'Listen to me first before beating me.'
Cheng then started slapping Chui across the face as he screamed, 'You're slandering me!', and urged the other girl to corroborate his story.
As other bystanders started to intervene in the altercation, Cheng shouted, 'None of your business!'
Most witnesses took Chui's side, with one woman telling him: 'Stand up, ditch this ugly girl, you deserve better.'
If this were your brother, how will you react?
Only in Asia!