Learn Hardcore Dutch: Sinds zij samenwonen, delen zij de taken eerlijk. - Since they have been living together, they share the tasks fairly.

Because sinds introduces a subordinate clause. In Dutch subordinate clauses, the finite verb goes to the end (verb-final). With separable verbs like samenwonen, the parts are written together at the end.

Main clause: Zij wonen samen.
Subordinate clause: Sinds zij samenwonen... Note: samenwonen here is the present tense, 3rd person plural. It looks like the infinitive because plural present forms end in -en, just like the infinitive.

Why is it delen zij and not zij delen after the comma?

Dutch main clauses are verb-second (V2). The entire subordinate clause (Sinds zij samenwonen) occupies the first position of the sentence, so the finite verb of the main clause (delen) must come next, before the subject:

Sinds zij samenwonen, delen zij de taken eerlijk. If you start with the subject instead, you don’t front a clause and you get:
Zij delen de taken eerlijk sinds zij samenwonen.

Can I use ze instead of zij?

Yes. Zij is the stressed (emphatic) form; ze is the unstressed form. Both are fine here:

Sinds ze samenwonen, delen ze de taken eerlijk. Use zij if you want contrast or emphasis on the subject.

Is the comma after the first clause required?

It’s strongly recommended but not strictly mandatory. Dutch commonly uses a comma between a fronted subordinate clause and the following main clause for clarity:

With comma (preferred): Sinds zij samenwonen, delen zij de taken eerlijk.
Without comma (acceptable in some styles): Sinds zij samenwonen delen zij de taken eerlijk.

Why is Dutch using the present tense with sinds, when English often uses the present perfect?

With sinds, Dutch typically uses the present to express a situation that started in the past and still holds:

Sinds zij samenwonen, delen zij de taken eerlijk. English would often say: They have been sharing the tasks fairly since they moved in together. If the whole situation is in the past and has ended, you use the past:
Sinds zij samenwoonden, deelden zij de taken eerlijk, maar later niet meer.

Is samenwonen a separable verb? How does it behave?

Yes. samenwonen (to live together) is separable.

Main clause (present): Wij wonen samen. (separated)
Subordinate clause/infinitive: dat wij samenwonen; We willen samenwonen. (together)
Perfect tense: We hebben samengewoond. (the ge- goes between the prefix and the stem)
With te-infinitive: om samen te wonen (the prefix stays with the verb)

Can I say Sinds zij wonen samen?

No. In subordinate clauses the verb goes to the end and separable verbs are not split. Correct is:

Sinds zij samenwonen Incorrect:
Sinds zij wonen samen

Can I place the sinds clause at the end of the sentence?

Yes:

Zij delen de taken eerlijk sinds zij samenwonen. When you don’t front the subordinate clause, the main clause keeps standard SVO order (Zij delen...). No inversion is needed there.

What’s the difference between delen and verdelen here?

delen = to share something (general). With taken, it implies they share or split the chores between them.
verdelen = to divide up/apportion something among people, often emphasizing the allocation process. Both can work: Ze delen/verdelen de taken eerlijk. verdelen slightly stresses the act of assigning who does what.

Do I need met elkaar or onderling to show they share with each other?

Not required. Delen de taken already implies the tasks are shared among them. You can add emphasis:

Ze delen de taken eerlijk met elkaar.
Ze verdelen de taken eerlijk onderling.

Why is it de taken? Could I omit the article?

de taken = the tasks (a specific, known set, e.g., household chores).
taken (no article) = tasks in general or some tasks (indefinite plural). Both are grammatical; the definite article is more natural here because it refers to the shared household chores.

Why does taak become taken (not taaken)?

Dutch spelling rules:

taak has a long vowel written aa in a closed syllable.
In the plural ta-ken, the first syllable is open, so a single a is enough to mark the long sound. Hence: taak → taken.

Is eerlijk an adverb here? Should it be eerlijk or eerlijke?

Here eerlijk modifies the verb phrase (how they share), so it’s an adverb and does not take -e:

Zij delen de taken eerlijk. As an adjective before a noun, you use eerlijke:
een eerlijke verdeling van de taken.

Can I say Sindsdat or Sinds dat zij samenwonen?

Sinds
- clause is the most idiomatic: Sinds zij samenwonen...
Sindsdat (one word) exists but is formal/old-fashioned.
Sinds dat (two words) is widely discouraged in standard written Dutch. Prefer plain sinds.

How do you pronounce the sentence?

Approximate IPA: [sɪnts zɛi ˈsaːmənˌʋoːnə(n), ˈdeːlə(n) zɛi də ˈtaːkən ˈeːrlək] Rough cues:

Sinds: sints
zij: zay (with a short e-glide)
samenwonen: SAH-men-voh-nen
delen: DAY-len
taken: TAA-ken
eerlijk: AIR-lik