Love Affair: The Taste of Cheating(2016)

Wealthy writer Sang-hyeon is in a slump and drinks every day. One day, he's on his way home drunk and witnesses a woman being bullied by strangers in the neighborhood, then helps her. He picks up a necklace that she might have dropped during the struggle. He hangs it up next to his computer as he works but for some reason, work is easier than he thought. However, his girlfriend throws away the necklace thinking it's bad luck and Sang-hyeon hurts his hand trying to look for it. He hires an operator to substitute type for him and Yena comes along. She's clumsy but bright and helpful. The closer they get, the more Sang-hyeon's girlfriend gets suspicious...