Breakdown of Hän ei koskaan kiitä minua.
minä
I
hän
he / she
ei
no / not (en, et, ei, emme, ette, eivät)
koskaan
never / ever
Questions & Answers about Hän ei koskaan kiitä minua.
Why is minua in the partitive case here?
The verb kiittää (to thank) requires the person you are thanking to be in the partitive case. This is a rule you just have to memorize for this verb! Because of this, the basic word minä (I) changes to its partitive form, minua (me).
Why does the sentence use ei koskaan instead of a single word for "never"?
In Finnish, "never" is usually built by combining the negative verb (here, ei) with the word koskaan (ever). You are literally saying "He doesn't ever thank me."
Why is the verb kiitä instead of kiittää?
In negative sentences, the main verb drops its personal ending. To find the correct form, you take the basic "I" form (minä kiitän) and remove the -n to get the negative stem: kiitä. This is the form you use after the negative verb ei.
Wait, the dictionary form kiittää has two T's. Why does kiitä only have one?
This happens because of a spelling rule called consonant gradation. When we make the "I" form (kiitän), the double tt weakens to a single t. Since the negative form kiitä is built from that "I" form by dropping the -n, it keeps the single t.