Why once you deceive a man, he will always be suspicious, because the trust mechanisms of men and women are completely different. A woman's trust is emotional; it can be rebuilt based on atmosphere, mood, or even a moment of being touched. A man's trust is a one-time switch; once you deceive him once, it causes structural damage. His default assumption about you will completely collapse, and his brain will permanently activate a defense mechanism, making it impossible to trust you unconditionally like before.