Everything you ever knew is not true.

When you react strongly or tell someone that their behavior is hurting you, a good friend or partner will work to improve & avoid that behavior in the future. Unfortunately, psychopaths do the exact opposite. When they notice that a certain behavior is upsetting you, they adopt it as a new "strategy". The stronger you react, the better the strategy. If the silent treatment makes you beg and plead, they'll start giving you more silence. If hints of cheating & infidelity make you cry, they'll start tossing in more and more of those subtle suggestions. Our assumption is that all humans feel remorse when they see someone else in pain, but psychopaths exploit these most vulnerable cries for help and then amplify whatever is causing it.