Benson claimed that he was supportive of Olsen despite there being a number of minor issues throughout her employment.
In October, Benson suddenly cut Olsen's hours without consulting her.
At a meeting about the change of hours, Olsen said Benson "had a real go at her" and called her unprofessional.
The ERA said it was likely that Benson had become tired of out-of-work issues in Olsen's personal life impacting her work.
"An employer is of course able to raise concerns with an employee but this should be done in a way to ensure that the relationship is not damaged.
"The way the concerns were raised and the very general nature of them meant Olsen was not able to respond to them. It was unfair and it impacted on Olsen's confidence," the ERA said.
The ERA ruled that Peninsula Health had breached its obligations of good faith by failing to be responsive and communicative, and that cutting her hours without consultation was unfair.
Olsen was awarded $9620 in lost wages and $15,000 in compensation for the stress she endured.