"He said he had to quit, 'because I couldn't stomach working with this guy any more'," Whitehead said. "He was upset, he'd been there 18 months and he'd put his life and soul into it. He was a farm manager and he was trying to make a good impression."
The man, who separated from his wife after the discovery, wanted to know if he had a case of constructive dismissal.
Whitehead told him he might have. "It's not illegal to have sex, even with someone else's wife. [But] everyone knows what the wife and the farmer did was wrong, it's a breach of fidelity, both by the wife and by the employer.
"And there is such a thing in law with employers and employees. There's an implied obligation in every employment agreement that each party has to have an obligation of fidelity, and trust and confidence run alongside that."
For employees that could mean not revealing an employer's intellectual property, Whitehead said.
For employers, it could mean providing a safe workplace. "They've got to trust their employer's not going to beat them or bash them, and that they're not going to have sex with their wife."
Dundas Street Employment Lawyers' partner Blair Scotland said the farm worker could have a case.
Staff and bosses didn't have to like each other, but they did need to be able to work together in a way that did not damage the business, Scotland said.
"I think we could raise an argument that sleeping with a subordinate's wife is a breach of that."