The chief executive officer of Highmark Inc. is facing charges of simple assault and defiant trespass relating to a fight with the husband of an employee with whom he was reportedly having an affair.

Kenneth Melani, 58, was charged Wednesday by Oakmont police. Melani allegedly showed up Sunday afternoon at the home of Mark Myler, who is married to Melissa Myler.

Melissa Myler told officers she has been having an affair with Melani since shortly after he hired her to work at Highmark in October 2011. In January, according to a criminal complaint, Melani’s wife discovered the affair and told Mark Myler.

That prompted Melissa Myler to move out of their home on Canterbury Court in Oakmont and in with Melani, according to the complaint.

Highmark spokesman Michael Weinstein said in a statement that the situation is a personal matter and that Melani is taking an unpaid leave from the company.

Melani’s attorney, Robert Del Greco, did not immediately return a call seeking comment.

A woman who answered the phone at Melani’s home in Cheswick said he was not home and hung up the phone.