Illicit sex is not invisible
A person enjoys illicit sex, and due to his blind, lusty desire. he thinks that no one can see him, but this illicit sex is thoroughly observed by the agents of the Supreme Personality of Godhead. Therefore the person is punished in so many ways. presently in Kali-yuga there are many pregnancies due to illicit sex, and sometimes abortions ensue. These sinful activities are witnessed by the agents of the Supreme personality of Godhead, and a man and woman who create such a situation are punished in the future by the stringent laws of material nature (daivi hy esa guna-mayi mama maya duratyaya). Illicit sex is never excused, and those who indulge in it are punished life after life.
Srimad Bhagavatam 5.14.9 purport