Undercover investigator of a married woman who loves her target

As an investigator who fake marriage to the target in order to carry out his mission, I had to continue my surveillance life as the target's wife until the day when the target showed great movements, despite being tormented by guilt towards my real husband. A year later, there were no signs of the target moving, and the days continued so calm that I wondered if they were really an operative. Even though it was a mission, I was in a long life as a married couple, and eventually I was drowning in rough sex with my target. One day, an unexpected situation reveals my identity...