A federal appeals court has thrown out a University of Denver professor’s claim that he experienced a hostile work environment and was the subject of employment discrimination based on his gender.

On Friday, a three-judge panel of the U.S. Court of Appeals for the 10th Circuit agreed with a lower court judge that Ron Throupe, an associate professor in DU’s real estate and construction management school, had not experienced treatment that was severe or pervasive in his job.

“Not all offensive or hurtful conduct within the workplace is actionable,” wrote Chief Judge Timothy M. Tymkovich in the appellate panel’s order.

Throupe’s lawsuit against the university stemmed from a personal and professional relationship he had with a female student from China. After she started working as his graduate assistant around 2013, he brought her to a faculty gala in lieu of his wife. Subsequently, he alleged, rumors arose in the school about a romantic relationship.

U.S. District Court Senior Judge Marcia S. Krieger wrote in her dismissal of the case that one student services director was concerned Throupe’s relationship with the student “surpassed the boundaries of what was acceptable.” It also became known that the student was solely taking classes with Throupe and was even on his family’s cell phone plan. At one point, when she stopped attending his classes, he went to coffee shops and questioned her friends about her.

Barbara Jackson, the director of the real estate and construction management school, wrote about Throupe in an email that “his behaviors have been totally unprofessional and inappropriate, his father/daughter views perverted, and his obsession out of control.” The school gave Throupe a warning that he was not to interact with the student as he had been.

Throupe argued to the court that DU targeted him as “a man having an affair because he did not conform to typical notions about how a man should act with the opposite sex.” He said Jackson gave him “unfavorable course schedules” and yelled at him.

The complaint also contended that the university would not have treated him similarly if he were a female employee having the same relationship with a male student. Throupe’s 2017 complaint cited a violation of Title IX, which prohibits discrimination based on sex in federally-funded education activities.

In affirming the dismissal, the appellate panel agreed Throupe had not provided evidence that the rumors of his affair were motivated by his sex. The warning the school provided him about his behavior stemmed from concerns of appropriate professor-student interactions, not merely because Throupe was male.

“Throupe has failed to raise any inference of discrimination. He has provided no evidence that a similarly-situated female professor would be treated differently,” wrote Tymkovich. “Rather, the record reflects that Throupe had male colleagues within the department who were also treated poorly in an effort to make them leave. But he also had male colleagues who were given more favorable assignments.”

A university spokesperson declined to comment on the case. Throupe told Colorado Politics he felt “very disappointed and been depressed and feel isolated for years.”

The case is Throupe v. Univesity of Denver et al.