The texts accused the woman of cheating on him and demanded that he be able to inspect her to confirm she hadn't. She repeatedly told him to leave her alone but he continued to send her messages.
They had been in a relationship for seven months, during which time police recorded 13 family violence callouts involving them.
Cox has also pleaded guilty to a charge of failing to stop after a police pursuit was abandoned on Kennedy Rd, Napier, on April 13, 2021, when Cox reached 80km/h in a 50km/h area.
However, he denied several other charges, for which he elected a judge-alone trial.
These charges included assault on a person in a family relationship, intimidation, threatening to cause grievous bodily harm and attempting to pervert the course of justice.
The trial was set down to be heard by Judge Bridget Mackintosh in the Napier District Court on Friday. James Bridgman appeared for the Crown and Philip Jensen was the defence counsel.
However, the judge was told that Cox's victim was unable to give evidence from an AVL room at the Rotorua courthouse because there was no one to sit with her in the room.
Court staff informed the judge that protocol required a police officer or victim adviser to be present when she gave evidence. None was available. Bridgman said efforts had been made to find such a person since Thursday afternoon.
Judge Mackintosh initially said she found the situation "bizarre" and a "bit of a shambles" but the Crown and court staff explained that it had been difficult to make arrangements because of the summer break, shortages of staff in both places, and Covid protocols.
Judge Mackintosh adjourned the case until next Friday, January 28, when it will be heard by Judge Geoff Rea.
Cox was remanded on bail until that date.