According to local reports, Vladimir Krasnov, 28, of Nizhny Novgorod had decided to make good on the oft-heard threat following a drunken fight with his 48-year-old friend Sergei over Krasnov's girlfriend Yelena.
Sergei suffered severe internal bleeding as a result, and eventually died at the scene.
Krasnov was subsequently arrested, and now faces up to 15 years behind bars.
"All I can say [is] I really regret [it]," Krasnov told officials. "Nothing like this would happen if I were sober."
His girlfriend Yelena concurred. "It's just alcohol," she told a reporter, adding that Krasnov had nothing to be jealous about.
"With [Sergei] it was just 'hello' and 'goodbye'," she said.