Min veninde kunne ikke indrømme sin fejl i går, men i dag siger hun, at det var hendes skyld.

In a Danish main clause, the finite verb normally comes in second position. Here, the finite verb is kunne, so it comes before ikke:

Min veninde kunne ikke indrømme ...

A useful rule is:

• in main clauses: finite verb + ikke
• in subordinate clauses: ikke usually comes before the finite verb

So compare:

• Hun kunne ikke indrømme det.
• ... at hun ikke kunne indrømme det.

Literally, kunne ikke means could not. But in a sentence like this, it often has the broader sense of couldn’t bring herself to admit it — for example because of pride, embarrassment, or stubbornness.

If you wanted to clearly say she refused / didn’t want to, Danish would more likely use ville ikke:

• Hun ville ikke indrømme sin fejl = She wouldn’t admit her mistake

So kunne ikke can sound a bit softer or more psychological than simple refusal.

Because Danish uses the reflexive possessive sin/sit/sine when the possessor is the subject of the same clause.

In:

Min veninde kunne ikke indrømme sin fejl

the subject is min veninde, and the mistake belongs to her, so Danish uses sin.

Very roughly:

• sin fejl = her own mistake
• hendes fejl = her mistake (but usually not reflexive, so it may sound like someone else’s)

This is one of the most important Danish grammar points for English speakers.

Because sin/sit/sine must agree with the noun being possessed:

• sin for common gender singular
• sit for neuter singular
• sine for plural

Fejl is a common gender singular noun, so the correct form is sin fejl.

Examples:

• sin bog = her/his own book
• sit hus = her/his own house
• sine bøger = her/his own books

Because a possessive already fills that slot.

In Danish, you do not say something like sin en fejl or sin fejlen. You simply say:

• sin fejl = her own mistake
• hendes bog = her book
• min ven = my friend

So the possessive word replaces the need for an article.

These are fixed Danish time expressions:

• i går = yesterday
• i dag = today
• i morgen = tomorrow

The i is just part of the normal expression. For learners, it is best to memorize them as whole phrases rather than trying to translate the i literally every time.

Because Danish main clauses follow the V2 rule: the finite verb must come in second position.

Here, i dag is placed first for emphasis, so the verb siger must come next:

• men i dag siger hun ...

That pushes the subject hun after the verb.

This is very common in Danish:

• I dag siger hun det.
• I går kunne hun ikke indrømme det.

If the subject comes first, then the verb follows it:

• Hun siger det i dag.

The comma before men separates two full main clauses:

• Min veninde kunne ikke indrømme sin fejl i går
• men i dag siger hun ...

The comma before at marks the start of a subordinate clause:

• ... siger hun, at det var hendes skyld

A small extra note: in Danish, comma rules around subordinate clauses can vary depending on whether someone uses start comma or not. So you may sometimes see at without a comma before it in modern Danish. But the version with the comma is very common and fully standard in systems that use start comma.

Because the sentence talks about two different times:

• i dag siger hun = today she says → present time
• det var hendes skyld = it was her fault → the fault belongs to the earlier situation

So the reporting verb is present, but the content of what she says refers to something in the past. This works just like English:

• Today she says that it was her fault.

Because sin can only refer back to the subject of its own clause.

In the clause:

at det var hendes skyld

the grammatical subject is det, not hun. Since hun is not the subject of that clause, Danish cannot use the reflexive sin there. So it uses the ordinary possessive hendes.

This is a very common contrast:

• Hun indrømmede sin fejl.
  subject = hun → reflexive sin

• Hun sagde, at det var hendes skyld.
  subject of subordinate clause = det → ordinary hendes

Because det var hendes skyld is a fixed, natural Danish way to say it was her fault.

Here det works like English it in expressions such as:

• It was my fault
• It was her fault

So det does not refer to one specific object in a strong concrete way here; it helps form the idiomatic expression.

In this sentence, skyld means fault, blame, or responsibility.

So:

• det var hendes skyld = it was her fault
• hun havde skylden = she was to blame

It does not necessarily mean legal guilt. In everyday Danish, skyld often just means that someone is responsible for something bad that happened.

Yes, quite often in spoken or informal Danish, especially after verbs like sige:

• ... siger hun, det var hendes skyld

That is common and natural in speech. But using at is also completely correct and often clearer, especially in writing:

• ... siger hun, at det var hendes skyld

So for learners, keeping at is usually the safest choice.