Learn Hardcore Dutch: De koelkastdeur blijft soms open, waardoor de yoghurt niet koud blijft. - The fridge door sometimes stays open, which means the yogurt does not stay cold.

Dutch often prefers blijven + adjective for a situation that continues or keeps happening, especially when that situation is a bit unwanted or accidental.

De koelkastdeur blijft soms open.
→ The door (tends to / ends up) staying open sometimes; it doesn’t get closed again. There’s an idea of persistence or repeated outcome.
De koelkastdeur is soms open.
→ The door is sometimes open (that’s just its state at certain times). This sounds more neutral and less like a problem.

So blijft open suggests a problematic, continuing state (people forget to close it), which fits the context of the yogurt not staying cold.

Why does soms come after blijft: blijft soms open and not soms blijft open?

In Dutch main clauses, normal word order is:

Subject – Verb – (Time/Manner/Place etc.) – Rest

So:

De koelkastdeur (subject)
blijft (verb)
soms (adverb of frequency)
open (adjective/predicative)

You can say Soms blijft de koelkastdeur open, but then soms is moved to the front for emphasis:

Soms blijft de koelkastdeur open.
→ Sometimes the fridge door stays open. (focus on sometimes)
De koelkastdeur blijft soms open.
→ The fridge door stays open sometimes. (a bit more neutral)

Both are correct; the given sentence just follows the neutral Subject–Verb–… pattern.

Why is blijft used twice: blijft soms open and niet koud blijft?

It’s the same verb blijven, but with two different adjectives:

blijft … open → stays/remains open
niet koud blijft → does not stay/remain cold

Dutch often uses blijven + adjective where English uses:

stay (the door stays open)
keep / stay (the yogurt doesn’t stay cold)

So the repetition is natural in Dutch:

De koelkastdeur blijft soms open, waardoor de yoghurt niet koud blijft.
→ The fridge door sometimes stays open, which means the yogurt doesn’t stay cold.

What exactly does waardoor mean here, and how is it different from dus or omdat?

waardoor literally combines waar (what/which) + door (through/by), and here it means:

waardoor → as a result of which / which causes / thereby

So:

…, waardoor de yoghurt niet koud blijft.
→ …, which causes the yogurt not to stay cold.
→ …, and because of that the yogurt doesn’t stay cold.

Differences from common alternatives:

dus = so / therefore
- De koelkastdeur blijft soms open, dus de yoghurt blijft niet koud.
  → More like a separate conclusion: The door sometimes stays open, so the yogurt doesn’t stay cold.
omdat = because (introduces a reason)
- De yoghurt blijft niet koud, omdat de koelkastdeur soms open blijft.
  → Reverses the order: The yogurt doesn’t stay cold because the door sometimes stays open.

waardoor keeps a tight connection to the previous clause and feels like “and because of that”. It’s especially natural when you keep the original order: cause first, effect second.

Why is the verb at the end in waardoor de yoghurt niet koud blijft?

Because waardoor introduces a subordinate clause. In Dutch subordinate clauses, the conjugated verb usually goes to the end:

Main clause: De yoghurt blijft niet koud.
(Subject – Verb – Negation – Adjective)
Subordinate clause (after waardoor):
…, waardoor de yoghurt niet koud blijft.
(Subordinator – Subject – Negation – Adjective – Verb)

So the pattern is:

Main clause: S – V – …
Subordinate clause: … – V (at the end)

That’s why you get … de yoghurt niet koud blijft, not … de yoghurt blijft niet koud.

Why is the negation niet before koud in niet koud blijft?

In subordinate clauses, you often get:

Subject – (other elements) – niet – Adjective/Participle – Verb

Here:

de yoghurt (subject)
niet (negation)
koud (adjective)
blijft (verb, at the end of the clause)

Compare:

Main clause: De yoghurt blijft niet koud.
Subordinate: … dat de yoghurt niet koud blijft.

So the niet still directly negates the quality koud, but the conjugated verb blijft has moved to the end because of the subordinate clause rule.

Could I also say … waardoor de yoghurt warm wordt instead of niet koud blijft?

Grammatically yes:

…, waardoor de yoghurt warm wordt.
→ “… which causes the yogurt to become warm.”

But the nuance is different:

niet koud blijft
→ Focuses on failing to stay cold (it loses its proper temperature, but not necessarily hot).
warm wordt
→ Suggests it becomes warm/hot, which might feel too strong if you simply mean “no longer properly chilled”.

In a fridge context, niet koud blijft sounds more natural: the problem is that it doesn’t remain chilled, not that it turns hot.

Why is koelkastdeur written as one word instead of koelkast deur?

Dutch almost always writes compound nouns as one word:

koelkast (fridge) + deur (door) → koelkastdeur (fridge door)

Writing koelkast deur would look wrong to a native speaker. Dutch compounds can get very long, but the rule stays the same: join the nouns into a single word.

Other examples:

huisdeur = house door
keukentafel = kitchen table
badkamerdeur = bathroom door

Why is it de koelkastdeur and de yoghurt? Could I leave out de before yoghurt?

Both koelkastdeur and yoghurt are de-words (common gender nouns), so they take the article de:

de koelkastdeur
de yoghurt

About dropping the article:

In English, you often say “yogurt” without “the” for a general statement.
In Dutch, you much more often keep the article with a specific mass noun:
- De yoghurt blijft niet koud.
  → A particular batch of yogurt in this fridge.

If you say just Yoghurt blijft niet koud, it sounds like a very general statement about yogurt as a substance (“Yogurt does not stay cold” as a universal truth), which doesn’t fit this context. So de yoghurt is the natural choice.

Could I also say De deur van de koelkast blijft soms open instead of De koelkastdeur blijft soms open?

Yes, both are correct:

De koelkastdeur blijft soms open.
→ Uses a compound noun; sounds very natural and compact.
De deur van de koelkast blijft soms open.
→ Slightly longer, a bit more explicit: “the door of the fridge”.

In everyday speech, koelkastdeur is more typical, because Dutch likes noun compounds. The meaning is the same.

Is there a difference between openstaan and open zijn / open blijven here?

All are possible but slightly different in feel:

De koelkastdeur blijft soms open.
→ Most natural here. Focus on the fact that it ends up remaining open.
De koelkastdeur staat soms open.
→ Describes its position/state (it is standing open) without stressing the idea that it “should be closed”.
De koelkastdeur blijft soms openstaan.
→ Combines blijven
- openstaan; more verbose but correct.
  → Slight extra emphasis on the ongoing state of being open.

In this specific context (a problem with yogurt not staying cold), blijft soms open is short, idiomatic, and fits best.