Police on Sunday night recovered two bodies from an abandoned house in Chattogram's Raozan upazila.
The deceased are Annesha Chowdhury Asha, 18, and Joy Barua, 26. Police suspect that Joy stabbed Annesha in the neck and then committed suicide by hanging, said officials after visiting the spot.
Annesha was a second-year student of Noapara Degree College in the upazila. Her father Ranjit Chowdhury is a businessman, while Joy's father runs a local tea-store.
Annesha family members said her wedding date was set on 10 March with an expatriate, and preparations were underway for the occasion.
The second-year student and her mother even did some shopping for the wedding on Sunday afternoon, and Annesha went for tuition after returning home.
Annesha did not have any love affair and she was excited about the marriage, according to the deceased's uncle Tiklu Barua.
Joy's father Nilendu Barua said his son came out of his tea-stall on Sunday evening to go to the temple. But he does not understand what happened after that.
The father said Joy was supposed to join a job from 1 March, and he had never heard of his son being in any affair.
However, Anwar Hossain, assistant superintendent of police (Raozan-Rangunia circle), said they suspect Joy killed the girl as he came to know about the marriage, and committed suicide subsequently.
He said police sent the bodies to Chattogram Medical College Hospital morgue for autopsy.