passive aggressive behaviour
Commonly described as non-verbal aggression, passive aggressive behaviour is when you are angry or upset with someone, but do not or cannot tell them. It is the inability to express difficult feelings in a rational way and can often make the problem worse. For the person on the receiving end, it can be incredibly frustrating and upsetting.
While some passive aggression can be unintentional (most of us will have behaved in this way at some point to avoid conflict) generally, the behaviour is intentional. Passive aggressive behaviour can manifest in many different ways. Someone who is passive aggressive may show resistance when asked to do something, through procrastination, disagreement or by being stubborn. They may refuse to be emotionally open - even if they are apparently angry or upset, they will insist they are fine, shutting down the conversation. They may even make excuses to avoid certain people.
Passive aggression is often considered a very destructive form of behaviour. When things aren't spoken about, the problem can only get worse - like a rot that is spreading. It is persistent and can eat away at the trust between people, breaking down many relationships.