Mobile phone footage shows the woman - backed by an angry mob who had blockaded the vehicle - grappling with the man when police eventually turn up to free the couple.
In the video, a huge crowd can be seen surrounding the vehicle and stopping it from being able to drive out of the busy public square in the centre of Lima, Peru.
They appear to be encouraging and backing the woman as she hits the man and rips his shirt.
The furious woman then repeatedly demands that the man opens the doors of the truck so she can face his alleged mistress.
Crowds watched as the incident unfolded
The woman appeared to be trying to get into the car
The incident happened in the centre of Lima, Peru
He refuses to open the doors and instead tries to calm her down as she gets increasingly angry.
The mob can be seen laughing and shouting as the woman repeatedly tries the door handles.
She then starts hitting and kicking the car to reach her who is thought to be her cousin inside.
The man on the ground as the woman appears to attack him
Police eventually showed up
Some onlookers allegedly then hand the woman items to smash the vehicle's windows and a couple even try to do the job for her, though without success.
She eventually smashes the glass as police arrive, it has been alleged.
The officers, in body armour and helmets, can be seen forcibly separating the bizarre love triangle.
Footage of the incident was posted on YouTube, where it has received more than 70,000 views.
The man's ripped shirt
Some viewers criticised the behaviour of both the woman and the mob who encouraged her.
Italo Luyo Alvare said: "Pack of ignorant, savage, gossip-hungry people. Everyone recorded and endorsed this maltreatment.
"Regardless of the reason, do you think it's right? We have lawyers for this type of thing."