Banajit Boro (17) had gone to the house of the girl (16) at Kharghuli area of Guwahati yesterday with the proposal, police said today.
The girl and her parents along with some other people allegedly attacked the boy with sharp weapons, seriously injuring him following which he was admitted to hospital.
The girl was taken into custody under legal provisions for juveniles, while her parents were booked for voluntarily causing grievous hurt and attempt to murder (under sections 326/307 of IPC), the police added.