Marshall Rosenberg advises us to "Use anger as a wake-up call to unmet needs". Any time we experience anger, it is because there is a need that is not being tended to. And I think that whatever need we initially recognize as the impetus for our anger is usually just a superficial speck of what is really going on internally; I think there is almost always a deeper need at play.
When I teach Nonviolent Communication through The Bigbie Method, I emphasize this idea of a "deeper need" when teaching the self-empathy process. Anytime someone shares anger as an emotion, I am hyper-alert to listen for what that deeper need might be, because underneath all anger is something tender and vulnerable. I think anger is the front we use to protect ourselves from the suffering of mourning a deep need. I've found that those deep needs are the ones that are harder to pinpoint because they are difficult to accept. These deep needs behind anger usually tell us something about ourselves that we aren't super keen on.
Here is an example. I recently spoke to someone who was frustrated, angry, and confused because they had not heard from the person they were dating in several days. After various calls and texts, this other person had not answered them, and they had thoughts they were being "ghosted". This person initially claimed mourning needs around clarity and communication. Sure, those make sense. But that wasn't what was really driving all the charge and feelings of frustration. After some digging, we uncovered the deeper need: acceptance. Specifically, self-acceptance and self-love. This revelation came from the vulnerable acknowledgement that they tend to seek external validation from others, and that is how they typically try to get needs met around acceptance. So the thought of being "ghosted" by a romantic interest didn't meet their deep need for acceptance.
I believe we are all mourning deep needs. Some of them are ongoing mournings that we carry daily. Some of these mournings might stem from trauma or childhood. Those needs - the ones that have deep-rooted history for us - are often the ones that are the hardest to acknowledge. And I think anger is our way of protecting ourselves from having to face them.
Anger is often focused on other (sometimes on self, too, but I'm specifically talking about external anger here). Marshall Rosenberg also says "[Anger] indicates that we have moved up to our head to analyze and judge somebody rather than focus on what we are needing and not getting". When we are analyzing and judging, we are not getting acquainted with our needs. When we are analyzing and judging, we are protecting ourselves by putting blame elsewhere instead of owning our need.
Realizing a deep need behind anger can be scary and intimidating, because it can bring up so much memory and/or emotion that may be hard to experience. It is a vulnerable process, but I have found it to be worth while every time, and I have heard similar sentiments from others whom I have worked with. Getting acquainted with a deep need gives me the clarity I need to let go of my anger, because usually it isn't really about the other, but rather about the self.