Unawareness here stands for our level of consciousness. For the same event, our understanding of ourselves, and our environment varies depending on our level of consciousness. It is the intellect that tells us that consequences of reacting negatively are not favorable. It is however the mind that reacts, based on impressions stored in it. If the mind is aligned with the intellect, then all is good, but the mind has its own ways, and does not always listen the intellect. Example - medical doctors very well know about the harmful consequences of smoking, but that does not stop them from smoking, as they are slaves of their mind, and the intellect is subdued.
A person who is more conscious, gets more reaction time, as his intellect alerts him to the anger in time and finds a reasonable and safe response. People who are less conscious are more at the mercy of their own mind, which reacts given the external stimulus. After the reaction, when the intellect kicks in, and more awareness dawns, one either starts either feeling guilty, or the ego finds a way to justify that the reaction was warranted, thanks to the external event. Thus, when we raise our level of consciousness through spiritual/self-help practices, we will get more and more time to respond, and our reactions will go down.
Each one of us is doing our best, with the level of awareness we have at each specific moment. Every negative reaction happens because of unawareness, and not malice, as we would like to think. As we raise our levels of consciousness by working on ourselves, our reactions go down and as a consequence, we naturally experience more peace within ourselves. This is an important thing for both parties involved in a negative situation to remember. Be quick in forgiving others, for they were only ignorant like a child. Also ask for forgiveness when needed and do forgive yourself, for in true repentence, your consciousness has already been elevated.