4. They lack empathy
One of the reasons psychopaths are so dangerous is that they usually do not have empathy for others. While most of us feel bad about even thinking about doing something awful to another human being, psychos do not have that standing in their way, making it much easier for them to do all kinds of unspeakable harm to others. This may also make them inclined to place the blame for relationship problems on their partner and refuse to admit any wrongdoing.