When it says don’t let the sun go down in your anger, it’s not about resolving the issue with the other person. It’s about resolving the issue within YOU.
Anger unresolved becomes offense planted as the seed of Unforgiveness, which takes root as bitterness. And bitterness? It bears the fruit of wrath. And it don’t take long to grow into unforgiveness, because wrath is you justifying to yourself why the person doesn’t deserve to be forgiven. And unforgiveness left without being uprooted hardens into pride. You’re choosing to stand in the spot of Judge, like you’re God, who is The Righteous Judge.
That’s your sin right there.
So don’t let the sun go down on YOUR anger. Resolve to forgive even if you yet disagree. Resolve to yield when you that the other person will not. Always always choose the path of meekness.