A 30-year-old man was stabbed to death in Uttar Pradesh's Hapur district on Sunday allegedly after he confronted his wife's paramour, the police said.
Ashok, a resident of Delhi, was killed in Sikheda village of Pilkhuwa, they said.
The accused, identified as Gagan, has been arrested, police officer Santosh Kumar said.
Ashok used to visit Gagan's house in Pilkhuwa. Gagan, too, frequented Ashok's residence in his absence. Over time, he engaged in an extramarital affair with Ashok's wife, the police said.
On Gagan's request, Ashok's wife accompanied him to Pilkhuwa. When Ashok called her, she informed him about her whereabouts.
Ashok and his friends arrived at Gagan's house. Ashok told Gagan he wanted to go along with his wife. Gagan attacked Ashok with a knife. His friends rushed Ashok to a hospital where he was declared dead.