The girl, identified as Afreen, yesterday threw acid over her lover, Suraj, a 22-year-old Dalit man, when he was leaving after her birthday celebration, they said.
The victim, who works in Haridwar, was rushed to a hospital with burn injuries on his face and body, they said.
According to Suraj's complaint, he and Afreen were in a love relationship since they were in college but recently his family arranged his marriage with another girl, police said.
The man has received 50 per cent burn injuries, they said.