Vinod Paswan, a resident of Mohiuddinnagar village in Samastipur district, was angry over the issue and shot and seriously injured his wife, they said.
"The woman was admitted to a hospital for treatment. But doctors referred to the Patna Medical College and Hospital as her condition deteriorated," a police officer said in Samastipur.
Police said they have registered a case against Paswan, who is absconding.
Ujiarpur is among seven Lok Sabha seats in Bihar that went to the polls Wednesday.