Learn Hardcore Swedish: Han blir stressad när det går fel. - He becomes stressed when it goes wrong.

Han blir stressad = He gets / becomes stressed
→ It describes that he changes from “not stressed” to “stressed” when something happens (when things go wrong).

Han är stressad = He is stressed
→ This just describes his current state, without focusing on what caused it.

In this sentence, the point is the reaction to things going wrong, so blir is the natural choice.

What exactly does blir mean here?

Blir is the present tense of bli (to become). In this type of general statement, Swedish present tense often corresponds to English gets or becomes:

Han blir stressad när det går fel.
= He gets stressed when things go wrong.

Even though we’re talking about a repeated or habitual reaction, Swedish still uses the simple present (blir), just like English uses gets in general statements.

Why is it det går fel and not something like saker går fel (“things go wrong”)?

Swedish very often uses det as a “dummy subject” in general situations, where English might say “things” or have no clear subject:

Det går bra. – It’s going well / Things go well.
Det gick dåligt. – It went badly.
Det går fel. – Things go wrong.

Using saker går fel (things go wrong) is possible, but sounds more concrete, as if we’re talking about specific “things” that go wrong.

Det går fel is more general and idiomatic, like English “when it goes wrong / when things go wrong” in a broad sense.

Why does går (literally “goes”) mean “go wrong” here?

Gå (to go, to walk) is also used idiomatically in Swedish to talk about how a situation turns out or develops, not about physical movement:

Hur gick det? – How did it go / turn out?
Det går bra. – It goes well / It’s going well.
Det går dåligt. – It goes badly.
Det går fel. – It goes wrong.

So in det går fel, går means something like turns out or goes, and fel describes how it goes (wrongly).

What is fel here? An adjective? An adverb? Why no ending?

Fel is a bit special in Swedish. It can be:

A noun:
- ett fel – a mistake / an error
An invariable “adjective-like” word meaning wrong/incorrect that doesn’t change form:
- Det är fel. – That’s wrong.
- Något är fel. – Something is wrong.
- Det gick fel. – It went wrong.

In det går fel, fel functions like an adverb or predicative complement meaning wrong(ly), and it never takes endings (fela, felet, fels etc. don’t exist in this sense). It stays fel in all genders and numbers in this usage.

Why is the word order när det går fel and not när går det fel?

This is about the difference between:

a subordinate clause introduced by när = when
a question starting with när = when?

In a subordinate clause, Swedish word order is:

[subjunction] + [subject] + [verb] …

So:

när det går fel – when it goes wrong (normal clause, not a question)

In a question, Swedish uses “verb-second” (V2) word order:

[question word] + [verb] + [subject] …

So:

När går det fel? – When does it go wrong? (a direct question)

In your sentence, när det går fel is not a question; it’s a when-clause, so the subject (det) comes before the verb (går).

What is the role of när here exactly?

Here när is a subordinating conjunction meaning “when” in the sense of whenever / every time that:

Han blir stressad när det går fel.
= He gets stressed when(ever) things go wrong.

It introduces a time clause that explains under what circumstances he gets stressed.

Note that när can also be a question word (When?), but in this sentence it’s clearly a conjunction, not a question.

Does stressad change form for gender or number?

Yes, stressad is an adjective (originally a participle) and it can change form, but in this sentence it appears in its basic form.

Indefinite forms:

en stressad man – a stressed man
ett stressat barn – a stressed child
stressade personer – stressed people

After bli and vara, you match the adjective to the subject:

Han blir stressad. – He gets stressed.
Hon är stressad. – She is stressed.
Barnet är stressat. – The child is stressed.
De blir stressade. – They get stressed.

Here the subject is han, so stressad is the correct form.

Could you also say “Han blir stressad när det blir fel”? What’s the difference from “går fel”?

Yes, Han blir stressad när det blir fel is grammatically correct and natural.

Nuance:

det går fel – focuses on the process or course of events going wrong (things go wrong).
det blir fel – focuses more on the result being wrong (it ends up being wrong / it turns out wrong).

Often they overlap and both can be used, but:

Det gick fel någonstans. – Something went wrong somewhere (along the way).
Det blev fel resultat. – The result was wrong.

In your sentence, both går fel and blir fel are possible, with a very small difference in emphasis.

Do you ever put a comma before när in this sentence?

In modern Swedish, you normally do not put a comma before a short när-clause that follows the main clause:

Han blir stressad när det går fel. ✅ (standard)
Han blir stressad, när det går fel. ❌ (usually avoided)

If you move the när-clause to the front, you can write:

När det går fel blir han stressad. ✅
(Some people insert a comma: När det går fel, blir han stressad. This is still seen, but current stylistic recommendations often prefer no comma unless the clause is long or needs special emphasis.)

So for your exact sentence with the clauses in this order, the correct, natural version is:

Han blir stressad när det går fel.