An "irresistible" Iowa dental assistant fired for threatening her boss's marriage -- even though she turned away his advances -- has lost her discrimination lawsuit.

Melissa Nelson, who is married with children, had worked for James Knight for 10 years before his wife complained about his infatuation with her.

Nelson told the court that she had seen Knight as a father figure and a man of "integrity" who generally treated her with respect.

But about nine years into the job, Knight started to complain that her clothes were "distracting" because they "accentuated her body," and he sometimes asked her to cover up with her lab coat.

At one point, Knight told Nelson that "if she saw his pants bulging, she would know her clothing was too revealing," court records showed.

After she told him that his complaint about the tightness of her shirt wasn't fair, he texted back that it was a good thing she didn't wear tight pants too "because then he would get it coming and going," the court records showed.

And at one point when Knight discussed infrequency in Nelson's sex life, he told her "that's like having a Lamborghini in the garage and never driving it."

Knight's wife, who also worked in the dental office, put her foot down when she discovered the two were texting each other.

After meeting with their pastor, Knight agreed to fire Nelson because she was a "big threat to our marriage."

Knight had his pastor by his side when he told Nelson that their relationship -- even if there was no sexual affair -- had become a "detriment" to his family and that for the sake of both their families they shouldn't work together.

He later told Nelson's husband she had not done anything wrong or inappropriate, but that he was worried "he would try to have an affair with her down the road if he did not fire her."

Since Nelson did not consider Knight's behavior to be sexual harassment, the Iowa Supreme Court determined the question to be "whether an employee who has not engaged in flirtatious conduct may be lawfully terminated simply because the boss views the employee as an irresistible attraction."

While Iowa law prohibits discrimination against employees based on gender, the all-male court ruled that Knight's conduct was "unfair" but "did not amount to unlawful discrimination."

"I'm trying to stay strong. It's tough," Nelson told CNN on Saturday, two days after the ruling was released. "I don't think it's fair. I don't think it's right."

She denied wearing provocative clothing, telling the television network she wore loose-fitting scrubs to work under her lab coat.

Knight's attorney said there was a clear precedent to allow employers to fire employees who aroused jealousy in their spouses.

"He and his wife really agonized about it," Stuart Cochrane told CNN. "He didn't want to terminate her."