The couple - Sandeep Singh and Monika - lived in the same village. On the basis of their school certificates, the girl was a minor while Sandeep Singh was 22 years old.
The couple had eloped from the Siwana village and the girl's family registered a complaint against Sandeep Aug 5.
This was the third case of the so-called 'honour killing' in Haryana in less than a month.
Earlier, a young couple was allegedly beaten to death by family members of the girl in a village in Rohtak district Aug 6.
Last month, a 21-year-old man was lynched for marrying against the wishes of his community in Haryana's Jind district.