Learn Icelandic: Við skildumst eftir spjallið. - We parted ways after the chat.

The base verb is skilja (to separate or understand). First, you conjugate it in the normal active simple past tense for við (we), which is skildum. Then, to make it middle voice, you simply add -st to the very end, giving you skildumst.

How does adding -st change the meaning from the regular verb skilja?

The active verb skilja usually means "to separate" or "to understand" and typically requires a direct object. When you add -st to make it middle voice, it takes on a reciprocal meaning: "to part ways" or "to separate from each other". It does not need an object because the action is happening mutually between the people involved.

Why is the word spjallið in the accusative case?

The preposition eftir governs the accusative case when it refers to time, meaning "after" a certain event. Since spjall (chat) is a neuter word, its accusative form with the attached definite article looks exactly the same as its basic nominative form: spjallið.

I remember eftir sometimes taking the dative case. Why not here?

This is a great refresher! When eftir means "after" regarding time, like in this sentence, it forces the following noun into the accusative case. However, when eftir means "along" a physical path or "remaining / left behind", it takes the dative case instead.