Learn Hardcore Croatian: Njena cura želi upoznati mog dečka u petak navečer. - Her girlfriend wants to meet my boyfriend on Friday evening.

njena cura = her girlfriend (most natural reading in modern speech)
It can also mean “her girl” (e.g. her daughter or her female friend) but that is less common and usually clear only from context.

So the default interpretation in a sentence like Njena cura želi upoznati mog dečka u petak navečer is:
Her girlfriend wants to meet my boyfriend on Friday evening.

Why is it njena cura želi and not njena cura žele?

The verb must agree with the grammatical subject, not with the number of people implied.

Subject: cura (singular, feminine)
Verb: želi – 3rd person singular, present (from željeti)

So:

Njena cura želi… = Her girlfriend wants… ✅
Njena cura žele… ❌ (that would be wrong, because cura is singular)

If the subject were plural, you would use žele:

Njene cure žele upoznati mog dečka.
Her girlfriends want to meet my boyfriend.

Why is it mog dečka and not moj dečko?

Because dečko is the direct object of the verb upoznati, so it has to be in the accusative case.

Nominative (subject): moj dečko – my boyfriend
- Moj dečko želi… – My boyfriend wants…
Accusative (object): mog dečka – my boyfriend (as an object)
- …želi upoznati mog dečka. – …wants to meet my boyfriend.

The possessive adjective moj also changes to match the case, gender, and number of dečko:

Nominative: moj dečko
Accusative: mog dečka

What’s the difference between mog dečka and moga dečka?

They are the same case and meaning (masculine singular accusative of moj dečko) – the difference is style and rhythm.

mog dečka – shortened form, very common in everyday speech and writing.
moga dečka – full form, slightly more formal or emphatic, often used in careful speech, poetry, or when you want a particular rhythm.

Both are correct:

Njena cura želi upoznati mog dečka. ✅
Njena cura želi upoznati moga dečka. ✅

Why njena and not njezina? Are both correct?

Both are correct; they’re just two standard variants of the same possessive adjective “her”.

Feminine singular nominative (for cura):

njena cura
njezina cura

They mean exactly the same. In practice:

njena is very common in speech and informal writing.
njezina can sound a bit more formal or “bookish”, but is also normal.

Similarly, for masculine nouns you’ll see njezin / njen etc.

Could it be svoja cura instead of njena cura? What’s the difference?

Svoj is a reflexive possessive (“one’s own”) and behaves differently from njena (“her”).

In your sentence, the subject is cura, so:

Njena cura želi… = Her girlfriend wants…
- “Her” refers to some other female person, not to the girlfriend herself.
- Example: Ana is sad. Her girlfriend wants to meet my boyfriend. → Njena cura želi… (njena = Ana’s)
Svoja cura želi… would mean Her own girlfriend wants…, but in practice this form is not used in this position; you normally use svoj when the possessor is the same as the grammatical subject.
- Ex: Ana voli svoju curu. – Ana loves her (own) girlfriend.
  - Here Ana is the subject, svou curu is the object, and svou refers back to Ana.

So in Njena cura želi upoznati mog dečka, njena must refer to someone else previously mentioned, not to the girlfriend herself. You would not say Svoja cura želi… here.

Why does želi use the infinitive upoznati? Could it be želi upoznavati instead?

In Croatian, verbs of desire or intention like željèti (“to want”) are typically followed by the infinitive of another verb. Here:

želi upoznati = wants to meet (once, to get acquainted)

The choice of upoznati vs upoznavati is about aspect:

upoznati – perfective, one-time event, completed meeting
- Njena cura želi upoznati mog dečka.
  Her girlfriend wants to (once) meet / get to know my boyfriend.
upoznavati – imperfective, ongoing or repeated process
- Njena cura želi upoznavati nove ljude.
  Her girlfriend wants to be getting to know / regularly meet new people.

So in your sentence, upoznati is the natural choice.

Why is there no preposition before mog dečka? Why not upoznati s mojim dečkom?

Upoznati can work in two slightly different constructions:

Direct object (what/who you meet or get to know):
- Želi upoznati mog dečka.
  She wants to meet my boyfriend.
Reflexive form upoznati se s + instrumental (to get acquainted / to get introduced to someone):
- Želi se upoznati s mojim dečkom.
  She wants to get acquainted with my boyfriend.

Both are correct, but:

upoznati + accusative is shorter and very common: “meet someone”.
upoznati se s + instrumental emphasizes the process of mutual introduction.

Your sentence uses the first, simpler pattern.

Is the word order fixed? Can I say Njena cura želi upoznati u petak navečer mog dečka?

Croatian word order is flexible, but not all positions sound equally natural.

Most neutral way here is:

Njena cura želi upoznati mog dečka u petak navečer.

Other acceptable options (with slight emphasis changes):

Njena cura želi u petak navečer upoznati mog dečka.
→ A bit more emphasis on when the meeting should happen.
U petak navečer njena cura želi upoznati mog dečka.
→ Strongest focus on the time (“On Friday evening, her girlfriend wants…”).

Your version Njena cura želi upoznati u petak navečer mog dečka is understandable, but many speakers would find the time expression more natural after the object, not between upoznati and mog dečka.

What exactly does u petak navečer mean? Could I just say u petak or navečer?

u petak navečer = on Friday evening. It combines day + part of day.

u petak – on Friday (any time that day)
navečer – in the evening (any day)
u petak navečer – specifically Friday evening

Other common variants:

u petak uvečer – very similar; uvečer instead of navečer
petak navečer – without u, more colloquial but common in speech

All are understandable; u petak navečer is very standard and clear.

Is navečer one word? What about na večer or naveče?

Standard Croatian uses navečer (one word).

navečer – in the evening, towards evening (standard)

You may also hear:

uvečer – synonym, also standard.
na večer – two words, more colloquial / regional; considered less standard.
naveče – typical in some regional varieties and in Serbian; in standard Croatian, navečer is preferred.

For learning standard Croatian, stick with navečer or uvečer.

Could I say djevojka instead of cura, or momak instead of dečko?

Yes, there are several near-synonyms, with slightly different tones:

cura – very colloquial, everyday; “girl”, often “girlfriend”.
djevojka – more neutral/formal; “girl/young woman”, also “girlfriend”.

So you could say:

Njena djevojka želi upoznati mog dečka.
(Still understandable as her girlfriend, but a bit more formal or ambiguous.)

For “boyfriend”:

dečko – common, informal, neutral: “boy”, “boyfriend”.
momak – also “young man”, “boyfriend”, often more regional or stylistic.

You could say:

Njena cura želi upoznati mog momka.

…but the most natural, modern everyday pair is cura / dečko.

How would I say “Her girlfriend and my boyfriend want to meet on Friday evening”?

You’d make both people the subject and keep upoznati se (“to meet each other” / “get together”) in the plural:

Njena cura i moj dečko žele se upoznati u petak navečer.

Here:

njena cura i moj dečko – compound subject (they)
žele – 3rd person plural of željeti
se upoznati – reflexive infinitive, “meet (each other)”.

This clearly shows that they want to meet each other, not that one wants to meet the other as a simple object.