Incomprehensible twisted logic

The Express Tribune on a really strange case of multiple murder:

Giving details of the murders, CCPO said that the killings were the outcome of a domestic dispute. He said Muhammad killed his wife after he found out about her alleged affair with a local drug peddler.

The accused, Muhammad, was an Afghan refugee and had settled in Peshawar 35 years ago and had later married Bano, who was a resident of Peshawar. They had two daughters.

Following the repatriation of Afghan refugees, Muhammad had decided to move back to Afghanistan to which Bano did not agree. The dispute later led to the accused killing the three victims.

His wife was cheating on him. So, why did he kill his daughters?