As they were walking along Victoria Street past the Wellington Central Police Station, he grabbed Belle by the arm, before pulling her by the hair.
A member of the public grew concerned with Bachop's actions towards his partner and tried to intervene, but he was pushed away by Bachop just as police arrived.
The former New Zealand Colts, Western Samoa and All Blacks player then became verbally abusive to police, before physically resisting arrest.
He was arrested and taken into custody, where police found a small amount of cannabis, as well as a pipe on him.
The court today heard how both Bachop and Belle believed he was guiding her, and he did not intend to hurt her.
In a victim impact statement Belle said "valuable lessons have been learnt and [our] relationship is even stronger''.
Belle and Bachop both have three children from previous relationships, and Belle - who walked in and out of court today holding Bachop's hand - is now pregnant with their first child.
But Judge Thomas said the member of the public had "significant concerns'' as he followed the pair and was shaken up by the incident.
"I suggest members of the public do not intervene lightly,''she said.
Bachop had written a letter to the judge accepting his irresponsible behaviour and accepted that at his age he should know better.
In sentencing Bachop, Judge Thomas said she had received positive references from many people about his character.
Bachop, who now works as a youth couching coordinator for the Wellington Rugby Board and Northern Wellington rugby club, had already paid a $500 donation to Women's Refuge and was doing counselling for drug and alcohol issues and a Living without Violence course.
His lawyer, Val Nisbet, argued for all four charges to be discharged without conviction, but Judge Thomas said she did not believe having convictions for assault would outweigh the seriousness of the crime.
However, she said travel could be a problem if Bachop received a conviction for the possession of cannabis and believed the charge outweighed the seriousness of the crime.
Outside court, Bachop and his partner did not comment, but Mr Nisbet said the pair would now carry on with the rest of their lives.
They thought the judge was thorough, but he would not comment on the sentence.
Bachop initially had name suppression but did not pursue it at a December hearing.
He said then, through Mr Nisbet, that he was not pursuing name suppression because he wanted to prevent any potentially negative impact on other former All Blacks.
Bachop initially pleaded not guilty to the charges but earlier this month changed his plea to guilty.