chinguga neujeodo museun iri saenggyeosseulkka geokjeongbuteo hajineun ma.

늦어도 is 늦다 + -어도, which usually means even if or even when.

So here, 친구가 늦어도 means something like:

• even if your friend is late
• when your friend is late
• just because your friend is late

The key nuance is concessive: the speaker is saying that your friend being late is not enough reason by itself to react in a certain way.

Here, 가 marks 친구 as the subject of the clause 친구가 늦어도.

Using 가 is natural because the sentence is talking about the situation of the friend being late. It presents that clause as the condition/background for the rest of the sentence.

If you used 친구는, it would sound more contrastive or topical, like:

• as for your friend, even if they’re late...

That is possible in some contexts, but 친구가 늦어도 is the more neutral and natural choice here.

This is a very common question.

• 늦으면 = if/when your friend is late
• 늦어도 = even if your friend is late / although your friend is late

The difference is nuance:

• -으면 is more neutral and conditional.
• -어도 has a stronger feeling of concession: that fact still doesn’t justify the reaction.

So in this sentence, 늦어도 works well because the speaker means:

• Even if your friend is late, don’t immediately assume something happened.

It pushes back against overreacting.

Literally, it is:

• 무슨 일 = what matter / what kind of thing / what happened
• 이 생기다 = for an incident/problem/situation to occur
• 생겼을까 = I wonder if something happened

So 무슨 일이 생겼을까 means:

• I wonder if something happened
• Could something have happened?
• Maybe something’s wrong?

In Korean, 무슨 일 often means something the matter or some problem, not just any random event.

So this phrase usually carries a slightly worried tone.

-을까 / -ㄹ까 often expresses:

• wondering to oneself
• speculation
• uncertainty

So 생겼을까 is not a plain statement like something happened. It means:

• I wonder if something happened
• Could something have happened?

In this sentence, it reflects the content of the worry: the speaker is telling someone not to start thinking maybe something happened just because the friend is late.

Good question. The difference is:

• 생길까 = I wonder if something will happen / might happen
• 생겼을까 = I wonder if something happened / might have happened

Since the friend is already late, the worry is that something may already have happened to cause the delay. That is why 생겼을까 is the natural choice.

So the sentence is not about a future possibility. It is about a suspected cause that may already exist.

Because with words like 걱정하다, Korean often allows the clause expressing the content of the worry to come directly before it.

So this pattern is normal:

• 비가 올까 걱정하다 = to worry that it might rain
• 늦지 않을까 걱정하다 = to worry that it might be late
• 무슨 일이 생겼을까 걱정하다 = to worry that something may have happened

In English, we often need that:

• worry that something happened

In Korean, that link is often built into the pattern itself, especially with -을까 걱정하다.

Here, 부터 means something like:

• starting with
• first of all
• right off the bat

So 걱정부터 하다 means:

• to start by worrying
• to worry first before anything else
• to jump straight to worrying

This is an important nuance. The sentence is not simply saying don’t worry. It is more specifically saying:

• don’t make worrying your first reaction

That 부터 adds the idea of sequence and priority.

-지는 마 is basically -지 마 with an added 는 for contrast or emphasis.

Compare:

• 하지 마 = don’t do it
• 하지는 마 = don’t do that, at least / don’t go doing that / specifically don’t do that

So 걱정부터 하지는 마 sounds a bit more pointed than 걱정부터 하지 마. It can feel like:

• At least don’t start by worrying
• Don’t go straight to worrying, okay?

The 는 often adds a mild contrastive feel, as if the speaker is saying:

• Whatever else you do, don’t do that first.

It mainly means:

• don’t jump to that conclusion first
• don’t immediately start worrying that something happened

That nuance comes from 부터 and -지는 마.

So the sentence does not necessarily mean:

• Never worry under any circumstances

Instead, it sounds more like:

• Don’t make that your first reaction just because your friend is late.

In other words, the speaker is discouraging an immediate worst-case assumption.

마 is a casual negative command, so the sentence is in an informal style.

That means it would naturally be used:

• with a friend
• with someone younger
• in casual speech

A more polite version would be:

• 친구가 늦어도 무슨 일이 생겼을까 걱정부터 하지는 마세요.

So the original sentence is casual but not unusually rough. It just sounds like normal spoken advice.