Observation Man (2019)

Newly married couple Eun-mi and Seong-soo look ordinary, but they both have their own secrets. Eun-mi enjoys calling her boyfriend to her home while her husband is away on work and Sung-soo enjoys watching his wife have sex with other men through the CCTV in his house. Not being able to get over the excitement he feels by doing that, he tells his wife everything and suggests she has sex with another man again...