The girl is a BA third year student at Narsingh Mahavidyalaya, and was attending tutorial classes at a coaching institute, where the owner's grandson committed the brutal act.
Gorakhpur Senior Superintendent of Police Ashutosh Kumar said Sonu talked to the girl on Tuesday while she was returning from the coaching institute and later cut off her nose.
Kumar said the mother of the girl brought her to Savitri hospital in Gorakhpur with the help of some villagers. She was later shifted to Gorakhpur medical college.
The SSP said the girl's marriage had been fixed last month and this angered Sonu.
However, Ashok, the girl's uncle, said she was walking home when Sonu and one of his friend came on a motorbike from behind and stopped her.
While Sonu's friend caught the girl's hands, Sonu chopped off her nose.
According to Ashok, Sonu then took the girl to his home in nearby Araw Jagdish village on his bike.
From there, the girl called up her mother and informed about the incident.
The girl lives with her mother, two sisters and one brother, while her father works at a private company in Delhi.
Sonu is yet to be arrested.
