Learn Hardcore Croatian: Nakon dugog razgovora došli smo do zaključka da kvaliteta prijateljstva ne ovisi o količini poruka na mreži. - After a long conversation we came to the conclusion that the quality of a friendship does not depend on the amount of messages on the internet.

razgovor (conversation) is masculine singular.
In the genitive singular, the adjective dug becomes dugog, and the noun razgovor becomes razgovora.

So:

nominative: dugi razgovor (a long conversation – subject)
genitive: dugog razgovora (of a long conversation – after nakon)

Pattern: nakon + genitive → nakon dugog razgovora.

Can I say poslije dugog razgovora instead of nakon dugog razgovora?

Yes. nakon and poslije both mean after, and both take the genitive case:

nakon dugog razgovora
poslije dugog razgovora

In everyday speech, poslije may sound a bit more colloquial; nakon slightly more formal or neutral, but they are both very common and interchangeable here.

Why is it došli smo and not smo došli? What’s the rule?

Croatian has a strong rule that clitic words (short, unstressed words like sam, si, je, smo, ste, su, se, ga, mu, ne etc.) tend to appear in second position in the clause.

In došli smo do zaključka:

The first element is došli.
The clitic smo immediately follows it, in second position.

You can also say mi smo došli do zaključka, where mi is first, and smo is still second. But smo došli at the very beginning of a clause is normally not allowed in standard Croatian.

Correct examples:

Mi smo došli do zaključka.
Nakon dugog razgovora, došli smo do zaključka.

Why is it došli and not something like došle or došla?

Došli is the past participle of doći in the masculine plural.

In Croatian, the past tense agrees with the subject’s gender and number:

Ja sam došao. (I came – male speaker)
Ja sam došla. (I came – female speaker)
Mi smo došli. (We came – group with at least one male / mixed group)
Mi smo došle. (We came – all female group)

The sentence uses došli smo, which implies:

either a group containing at least one man,
or just a neutral default masculine plural (often used in mixed or unspecified groups).

What exactly does the expression doći do zaključka mean? Could I just say zaključili smo?

Doći do zaključka literally means to come to a conclusion, and it’s a very common idiom.

doći do zaključka = to reach/arrive at a conclusion
zaključiti = to conclude

Both are correct:

Došli smo do zaključka da…
We came to the conclusion that…
Zaključili smo da…
We concluded that…

doći do zaključka can sound a bit more process-oriented (after thinking, discussing, etc.), whereas zaključiti is more directly to conclude. In your sentence, both would be natural.

Why is it do zaključka? Why genitive after do?

The preposition do (to, up to, until) normally takes the genitive case.

do kuće (to the house)
do grada (to the city)
do zaključka (to the conclusion)

So:

zaključak (nominative singular)
zaključka (genitive singular)

Because of do, we get do zaključka.

Is da here the same as English that? Does it change the verb form or word order?

Yes, da in this sentence functions like English that introducing a subordinate clause:

došli smo do zaključka da…
we came to the conclusion that…

Unlike some other languages, Croatian does not have a special verb form like the English subjunctive here. You just use the normal indicative:

da kvaliteta prijateljstva ne ovisi o količini poruka…

The word order inside a da-clause is generally similar to a main clause, but clitics (like ne, se, ga) still try to sit in the second position of the clause.

Why is it kvaliteta prijateljstva and not something like kvaliteta prijateljstava (plural)?

Prijateljstvo means friendship (singular, neuter). Here, we are talking about the quality of friendship (in general), not of multiple individual friendships:

kvaliteta prijateljstva = the quality of friendship

Grammatically:

prijateljstvo – nominative singular
prijateljstva – genitive singular

We use the genitive singular after kvaliteta to express “quality of X”.

If you really wanted “the quality of friendships” (many different friendships), you could say kvaliteta prijateljstava (genitive plural), but the given sentence is more general/abstract: friendship as a concept.

How does the verb ovisi work? Is ne ovisi just the negation?

The verb is ovisiti (to depend). In the present tense:

ja ovisim
ti ovisiš
on/ona/ono ovisi
mi ovisimo
vi ovisite
oni/one/ona ovise

In the sentence we have 3rd person singular: kvaliteta prijateljstva ne ovisi… – the quality of friendship does not depend…

Negation is formed by putting ne directly before the verb:

ovisi → ne ovisi
znam → ne znam
želi → ne želi

So ne ovisi = does not depend.

Why is it o količini poruka and not o količina poruke or something else?

The structure ovisiti o requires the locative case after o.

o + locative → o količini

količina (quantity, amount) is feminine singular:

nominative: količina
locative: u/o količini

Then poruke (messages) stands in the genitive plural after količina, because it’s “the amount of messages”:

količina poruka = the amount/quantity of messages

So:

o količini poruka = on / upon the amount of messages (i.e. on the number of messages)

Case breakdown:

o → triggers locative
količini → locative singular
poruka → genitive plural (after količina)

What does na mreži literally mean, and is it the same as online?

Literally, mreža means net or network.

na mreži = on the net / on the network

In context, na mreži is used to mean online, similar to na internetu (on the internet). In everyday Croatian, both are used:

poruke na mreži = messages online / on the internet
poruke na internetu = messages on the internet

So yes, functionally na mreži here means online.

Where does ne go in Croatian? Could I say kvaliteta prijateljstva ovisi ne o količini poruka?

In standard Croatian, ne normally goes right before the finite verb:

kvaliteta prijateljstva ne ovisi o količini poruka…

Putting ne elsewhere, like ovisi ne o količini, would sound marked or wrong in neutral speech. You can do some special word orders for emphasis, but the basic rule to learn is:

ne + verb → ne ovisi, ne zna, ne voli, ne može…

Can you summarize the cases used in this sentence?

Yes, here is a quick breakdown:

Nakon dugog razgovora
- nakon → genitive
- dugog razgovora = genitive singular (masc.)
došli smo do zaključka
- do → genitive
- zaključka = genitive singular (masc.)
da kvaliteta prijateljstva ne ovisi o količini poruka
- kvaliteta = nominative singular (subject)
- prijateljstva = genitive singular (of friendship)
- o → locative
- količini = locative singular (of amount)
- poruka = genitive plural (of messages)
na mreži
- na (here) → locative
- mreži = locative singular (on the net / online)

So you see mainly genitive (after nakon, do, količina) and locative (after o, na) in this sentence.