The real reason that person is making you angry includes you.
You can see it in the sentence structure: yes, the other person is angering you, but ‘you’ have to be a part of the sentence for that to occur.
So then, when we fixate on them inside our heads, and forget about us, we falsely remove the subject-object relationship that is fundamental to this state of anger.
Their behavior PLUS our response EQUALS our current emotional state.
The moment you notice yourself mentally pointing the finger at them, take a pause and ask yourself, ‘why is this so angering to me?’
When you can do that, you’ll often find that there’s something underneath the whole situation, something else that preceded this moment that was already upsetting you which is the ‘root cause’ of the problem.
Find that, and then you can relieve it.