A 19-year-old youth was arrested on Tuesday after he allegedly threatened his sister-in-law of throwing acid in Siyani Gate area in Ghaziabad.
Mohit Rana had married Payal against the wishes of her parents in March, according to the complaint.
Their families were against the relationship, police said.
Payal's sister Soni lodged a complaint against Mohit today after which he was arrested, they said.
Probe into the matter was on.
"In her complaint to police, Soni said that Mohit today (Tuesday) threatened her to throw acid on her following which we arrested him," a senior police officer.
"We are investigating allegations made by Payal's sister," he said.