The constable's father found his body at 6 AM in their home in Secunderabad.
G Thani had joined the police force as a constable in 2010.
"He came to the house at 2 AM and hanged himself to the ceiling fan of his room with a rope. At around 6 AM, his father noticed him hanging," police officer Harish Koushik told news agency PTI.
"No suicide note was found at the spot. However, preliminary investigations reveal that he fell in love with the woman while working in the Santoshnagar police station here earlier," he said.
According to the officer, G Thani was upset that the relationship had failed.
A case was registered and investigations are on.
(With inputs from PTI)