Sometimes the issue is small and the meaning attached to it is enormous.

The argument is about a forgotten errand and the weight is about whether you are held in mind at all. That is why the reaction seems out of proportion; it is proportionate to the meaning, not to the event, and the meaning is usually unspoken.

When a small thing produces a large feeling, ask what it stands for. Then talk about that instead. Arguing about the errand cannot resolve it, and naming the real thing often does so quickly.