When the pair began to argue he leaned over and punched her to the side of the head, causing her to lose consciousness, a police summary of facts stated.
Instead of seeking help, he continued to drive around while yelling at the woman "I will get rid of you".
He started to drive up a hill towards a lookout in the district, when he stopped the car and pushed her out.
After she was dropped at home, the woman sought medical help for her injuries.
A couple of months later, Nikotemo's violent streak reared its head again.
He was at the woman's house on May 10 when she received a phone call. After taking the call outside for privacy purposes, Nikotemo put his hand around her throat, pushed her and then punched her in the face.
The woman was treated at Taranaki Base Hospital for swelling to her face, a severely bloodshot eye and a sore neck.
In court, Nikotemo pleaded guilty to a representative charge of injuring with intent to injure and assault with intent to injure. The charges carry maximum penalties of five and three years' imprisonment, respectively.
He also admitted charges of common assault, wilful damage and behaving threateningly in relation to two separate incidents which involved the woman and her brother.
The guilty pleas followed a resolution being reached between police and Nikotemo, who originally intended to take the offending to trial.
Judge Lynne Harrison ordered a pre-sentence report with electronic options and referred the matter to restorative justice.
The bail condition not to contact the woman remains in place and Nikotemo will be sentenced on November 4.
