Police in Kushinagar stopped a wedding function and took the couple to the police station for interrogation after a complaint that it was an interfaith marriage involving a minor girl.
The man and the woman turned out to be both Muslims and adults.
The man told a newspaper later that he was thrashed with a leather belt at the station, an allegation denied by the police.
Kushinagar Superintendent of Police Vinod Kumar Singh said someone from Gurnia village had informed them on Tuesday that a couple was getting 'quietly' married there, and suspected it to be a case of 'love jihad'.
The term is used by right-wing activists to refer to marriages allegedly performed for the sake of religious conversion.
A police team reached the spot and found a 'maulvi' and the couple there and brought them to police station for interrogation, the SP said.
He said police later established that both were adults and belonged to the same faith.
The two eloped 13 days ago from Azamgarh and the woman's family had lodged a missing person's report at the police station, he said.
"No policeman beat the man or harassed the couple," the SP said.
He said after counselling by police on video call, the parents of both the man and the woman attended the wedding at Kasia in Kushinagar on Wednesday.
Arman Khan, a local social worker, also rejected the allegation that police beat up the groom.
"I was with them at the police station and no policeman had beaten them," he said.
He said some right-wing people had told police that it was a case of 'love jihad'.
"However, when police found that both were adults and also of the same faith, they talked to the woman's family on video call," he said.
The social worker claimed that the 'maulvi' too was not ready to perform the marriage and was seeking the presence of a lawyer of the woman's family members.
Khan said the groom has a shop at Gola bazar in Kasia and had sought his help to marry the woman, whom he had met on a train to Narkatiaganj in Bihar a year ago.
According to him, the two started talking on the phone and later decided to get married, but the woman's family did not initially agree to it.
The recently promulgated Uttar Pradesh Prohibition of Unlawful Conversion of Religion Ordinance punishes forcible or fraudulent conversions, and requires a two-month notice if some wants to convert.
The controversial law also nullifies marriages performed for the sake of conversion.
The UP Police have acted swiftly in recent days after being tipped off about interfaith marriages.
Last week, a ceremony in Lucknow was stopped with police asking the couple to meet with the the legal provisions first.
