The New Plymouth District Court heard how cheating claims had long plagued the foursome from Eltham township.

Love really does hurt for two men in relationships with identical twin sisters.

Michael Wayne Klenner and another man are in separate romantic relationships with the two sisters and the group all hail from Eltham, a small town in South Taranaki.

The New Plymouth District Court heard how cheating claims had long plagued the foursome and proved to be a trigger for Klenner's assault on his male love rival in April.

Brittany Baker Eltham in South Taranaki, where the drama took place.

The police summary of facts said Klenner came to blows with the man because he believed he had slept with his girlfriend.

"Fidelity is an ongoing issue within this group and is the cause of many domestic related occurrences requiring police attention."

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Brittany Baker Michael Wayne Klenner was jailed for six months for an assault connected to a toxic love quadrangle in the South Taranaki town of Eltham. (File Photo)

Acting on his latest suspicion, Klenner, 37, went to a North St address in Eltham on April 1 about 9.30am and found the other man lying on the couch.

Klenner punched his victim him in the head and then threw a small fan heater at him before he left the property.

The defendant drove off but the assault victim was in hot pursuit and followed Klenner in his car.

The pair stopped on opposite sides of High St before the assault victim did a u-turn in his vehicle and drove into the back of Klenner's car.

In retaliation, the defendant reversed his car and slammed into his rival's driver-side door.

Klenner then drove off and parked on the side of the road.

He approached the assault victim on foot and as the man pulled out into traffic, Klenner was hit by the car.

Defence lawyer Paul Keegan said the force of the impact saw Klenner "cartwheel" through the air and land heavily, causing the injury he still nursed in the dock on Friday. His right arm was observed to be resting in a bulky sling.

Klenner previously pleaded guilty to common assault, dangerous driving and an unrelated charge of breaching court release conditions.

His assault victim has also been charged in relation to the April 1 incident and is due to appear in the Hāwera District Court on Tuesday.

After Klenner waived his right to a pre-sentence report, Judge Chris Sygrove imposed a six month jail term for the common assault and a concurrent sentence of one month imprisonment for the driving charge.

Klenner was convicted and discharged for the breach and disqualified from driving for six months.