Cases were registered against the two for offences under IPC including illicit affair, criminal intimidation, using abusive language and dowry harassment, police said.
Acting on a complaint from the wife of the constable, District Superintendent of Police Rajendra Singh Bidari directed the Usilampatti All woman Police Station Inspector to register the cases.
The constable developed intimacy with the SI when he was working as Inspector's driver at Ezhumalai Police Station. His wife had reprimanded and asked him to give up the relationship, they said.
They, instead, had harassed the constable's wife, police said.