Stalker Half(2019)

Mi-jeong is a divorcee. On her way home after work one day, she feels she is being stalked by someone. She's scared to be home alone without even a husband, so she asks a close friend named Ji-hye to move in with her. Ji-hye, who needed a place to stay, moves in. With permission from Mi-jeong, Ji-hye brings her boyfriend, Geon-soo, into the house, and Mi-jeong starts developing feelings for him.