The girl is also missing, they said.
According to police, the youth, identified as Soni, had an affair with Paramjeet Kaur but their families were against the relationship.
On the night of June 24, Soni tried to meet Paramjeet but he was caught by her family members who dragged him into their house and beat him to death, they said.
On the statement of the deceased's mother, police have arrested Paramjeet's father Jagir Singh and two brothers Arvinder and Mangal.