The 18-year-old girl died on the way to hospital and the boy has been battling for life at Malda Medical College.
The duo were classmates at a college here and were planning to get married in February, police said.
However, the girl's family members were against her plans to get married to the boy as he belonged to another religion, they said.
The youth went to the girl's house this noon and shot the girl from a 9 mm pistol and then shot himself in the head, Superintendent of Police Kalyan Mukherjee said.
