Ms Baker began working as a marketing manager for Hauraki Rail Trail in January 2012, the authority said.
She was employed because she was involved in a romantic relationship with Mr Maynard at the time, and was living with him.
She told the authority soon after starting with the company she realised she didn't want to stay in the relationship.
She moved to her own house in June 2012, but continued to work for Hauraki Rail Trail.
Ms Baker told the authority Mr Maynard called her later that month and said he needed to get some "property" from her house which belonged to the company.
She alleged he then broke into her house, however, Mr Maynard said he had a key.
Matters then came to head when Mr Maynard collected some tools from Ms Baker's house.
Ms Baker said when she went to grab some papers from the car, Mr Maynard assaulted her.
She said following the incident, Mr Maynard said she would never see him again because she had lost her job.
However, Mr Maynard denied this and claimed he said: "I have had enough. I am out of here."
Mr Maynard was later found guilty of assault by jury.
He was found not guilty of allegations of breaking into Ms Baker's home.
Following the altercation, Ms Baker continued to receive wages from the company until the middle of July.
Authority member James Crichton said he had "no hesitation" in concluding the employment relationship could not continue following the assault.
"No employee ought to have to persevere with an employment relationship having been assaulted by the governing director of the employer."
He said Ms Baker had a personal grievance for unjustified dismissal and Hauraki Rail Trail breached its good faith obligations, and unjustifiably disadvantaged her by failing to provide a safe workplace.
Ms Baker was awarded $17,500 in compensation and $71.56 in filing fees.
Hauraki Rail Trail was also ordered to pay Ms Baker $1750 in costs.
A statement of problem was first filed with the authority in July 2013, however an investigation meeting was not held until August because the matter between Ms Baker and Mr Maynard was tied up in court.