Bana neden küstün?

Bana means to me.

It comes from the pronoun ben (I) plus the dative meaning to:

• ben = I
• bana = to me

This form is a little irregular. You might expect something like bene, but Turkish actually uses:

• ben → bana
• sen → sana

So bana neden küstün? is literally something like Why did you become offended to me?, which English expresses more naturally as Why are you upset with me? or Why did you get mad at me?

Because the verb küsmek takes the dative case, not the accusative.

• bana = to me / at me
• beni = me as a direct object

In Turkish, you do not choose the case based only on English logic; many verbs require a specific case.
Küsmek is one of the verbs that goes with the dative:

• birine küsmek = to be offended with someone / to sulk at someone

So:

• Bana küstün. = You got offended with me.
• not Beni küstün for this meaning

Küstün comes from the verb küsmek.

Küsmek usually means:

• to become offended
• to sulk
• to stop talking to someone because your feelings were hurt
• to be cross with someone in a somewhat emotional or personal way

So küstün means you became offended, you got upset, or you sulked.

Depending on context, English might translate it as:

• Why did you get upset with me?
• Why are you offended with me?
• Why are you mad at me?

It often suggests hurt feelings, not just ordinary anger.

It breaks down like this:

• küs- = verb stem
• -tü- = past tense suffix
• -n = you (singular)

So:

• küs-tü-n = you got offended / you were offended

Why -tü?

The Turkish past tense suffix is often shown as -DI, but it changes shape because of vowel harmony and consonant harmony.

Here:

• the stem ends in s, which is voiceless, so d becomes t
• the last vowel in küs is ü, so the vowel in the suffix becomes ü

That gives -tü.

Because Turkish often leaves out subject pronouns when the verb already shows the person.

In küstün, the ending already tells us the subject is you (singular).

So Turkish does not need sen here.

• (Sen) bana neden küstün? = Why did you get upset with me?

Both are possible, but sen is usually unnecessary unless you want extra emphasis or contrast.

Because this is a question-word question, not a yes/no question.

Turkish uses words like:

• neden = why
• niçin = why / for what reason
• ne zaman = when
• kim = who

When one of these question words is present, you usually do not use mi.

So:

• Bana neden küstün? = correct

But mi is used in yes/no questions, such as:

• Bana küstün mü? = Are you upset with me? / Did you get upset with me?

Yes, grammatically küstün is in the simple past.

Literally, it means:

• Why did you get offended with me?

But in real usage, it can also correspond to natural English like:

• Why are you upset with me?

That is because Turkish is often focusing on the moment the state began: you became offended.
If that offended state still continues now, English may prefer a present-sounding translation.

So the Turkish past tense here can easily produce an English present-style meaning depending on context.

Yes. Turkish word order is flexible.

You can say:

• Bana neden küstün?
• Neden bana küstün?

Both are natural.

The difference is mostly about emphasis:

• Bana neden küstün? puts a bit more focus on me
• Neden bana küstün? starts with why, which can feel slightly more neutral

Turkish often moves words around to highlight what is important.

Not exactly.

Küsmek usually suggests:

• hurt feelings
• sulking
• emotional offense
• withdrawing from someone
• sometimes not talking to them for a while

It is often more personal and softer than pure anger, though it can overlap with anger.

So Bana neden küstün? is often closer to:

• Why are you upset with me?
• Why did you get offended with me?
• Why are you sulking at me?

It is not always the same as strong rage.

Yes. Niye and neden both mean why in everyday Turkish.

So these are both natural:

• Bana neden küstün?
• Bana niye küstün?

Very roughly:

• niye can sound a bit more conversational
• neden can sound slightly more neutral or standard

But in normal speech, both are extremely common.

A simple pronunciation guide is:

BAH-nah NEH-den KUES-tuun

More carefully:

• ba-na
• ne-den
• küs-tün

A few key points:

• a is like the a in father
• e is like the e in bed
• ü does not exist in standard English; it is like German ü or French u
• stress is usually fairly even, but neden naturally has a clear first syllable: NE-den

So the hardest part for many English speakers is the ü sound in küstün.