Learn Hardcore Indonesian: Sahabat saya selalu mendukung saya ketika saya stres. - My close friend always supports me when I am stressed.

So sahabat saya is the natural way to say my (close) friend.
saya sahabat isn’t grammatical in this meaning; it would just sound like you put saya and sahabat next to each other without a clear relationship.

What’s the difference between sahabat, teman, and kawan?

All three can be translated as friend, but they differ in nuance:

sahabat
- Strongest sense of closeness, like close friend or best friend.
- Often implies a deep, long-term, or emotionally close relationship.
- Your sentence suggests this is a very important friend.
teman
- General word for friend or companion.
- Can be close or not-so-close, depending on context.
- Teman saya selalu mendukung saya ketika saya stres. = My friend always supports me when I’m stressed.
kawan
- Similar to teman, but feels a bit more literary, old-fashioned, or regionally marked in many contexts.
- Also sometimes used in political or organizational contexts (like comrade).

So sahabat saya is slightly stronger and more emotional than teman saya.

Why is saya repeated so many times? Can I say it fewer times?

Sahabat saya selalu mendukung saya ketika saya stres.

The sentence has saya three times:

sahabat saya – my friend
mendukung saya – supports me
ketika saya stres – when I am stressed

This is grammatically fine, but Indonesian often drops pronouns when they’re clear from context. Natural alternatives:

Sahabat saya selalu mendukung saya ketika stres.
- Drop the last saya.
- Still clearly “when I’m stressed”, because we know we’re talking about you.
Sahabat saya selalu mendukung saya ketika aku stres.
- Mixing saya and aku is possible but sounds a bit stylistically odd in one short sentence unless you have a reason.
Sahabat saya selalu mendukung saya ketika sedang stres.
- Drop saya and add sedang (see later question).
- Still implies when I am feeling stressed.

So yes, you can safely make it lighter and more natural by dropping the last saya:
Sahabat saya selalu mendukung saya ketika stres.

What does selalu do here, and where can it go in the sentence?

Sahabat saya selalu mendukung saya ketika saya stres.

selalu means always and usually goes before the verb:

Sahabat saya selalu mendukung saya... = My friend always supports me...

Other possible positions:

Sahabat saya mendukung saya selalu ketika saya stres.
- Grammatically possible but sounds less natural and more marked.
- Feels like you’re emphasizing always in a slightly unusual way.
Sahabat saya selalu mendukung saya ketika saya stres.
- Most natural, neutral word order.

So in everyday Indonesian, put selalu just before the main verb (mendukung) like in the original sentence.

Why is it mendukung and not just dukung?

dukung is the root (basic) form of the verb to support.
mendukung is that root with the meN- prefix:

meN- + dukung → mendukung

In standard Indonesian sentences, especially in writing or neutral/formal speech:

Transitive verbs (verbs that take a direct object) usually appear with meN- when used with an explicit object.

Here, saya is the object, so:

Sahabat saya mendukung saya. ✅ (standard)
Sahabat saya dukung saya. ❓ (sounds incomplete or nonstandard in most contexts)

You’ll hear bare roots like dukung in some colloquial speech (especially Jakartan Indonesian), but if you’re aiming for clear standard Indonesian, mendukung is the safer and more correct choice.

Also note related forms:

dukungan = support (noun)
- Dukungan sahabat saya sangat berarti. = My friend’s support means a lot.

What’s the difference between ketika, saat, and waktu? Could I replace ketika here?

All three can mean something like when (in a time sense), but with slightly different feels.

In your sentence:

Sahabat saya selalu mendukung saya ketika saya stres.
Sahabat saya selalu mendukung saya saat saya stres.
Sahabat saya selalu mendukung saya waktu saya stres.

All are understandable and basically mean the same thing. Nuances:

ketika
- Slightly more formal/neutral.
- Very common in writing, but also normal in speech.
saat
- Also quite neutral.
- Feels very natural in both spoken and written Indonesian.
- Many speakers would use this a lot in everyday conversation.
waktu
- Literally time, but can work like when.
- Sounds a bit more casual/colloquial in this usage.

So yes, you can replace ketika with saat or waktu here without changing the core meaning.

Is stres a noun or an adjective here? And why is it spelled stres, not stress?

In Indonesian, stres (a loanword from English) is commonly treated like an adjective, similar to tired, angry, sad:

Saya stres. = I am stressed.
Dia kelihatan stres. = He/she looks stressed.

It can also function more like a noun in some phrases, but in your sentence it’s adjectival: saya stres = I am stressed.

About the spelling:

Indonesian spelling: stres (one s at the end)
English spelling: stress

Indonesian phonetic spelling tends to simplify imported words and adapt them to Indonesian pronunciation and orthographic rules, so stress became stres.

Would Indonesians actually say saya here, or would they use aku or something like gue? How does the level of formality work?

Your sentence with saya is neutral–formal and perfectly correct:

Sahabat saya selalu mendukung saya ketika saya stres.

In everyday informal conversation, many speakers would use aku (or a regional variant), and shorten the object pronoun:

Sahabat aku selalu mendukung aku ketika aku stres. (standard informal)
More natural in speech:
Sahabat aku selalu mendukung aku waktu aku stres.
or
Sahabat aku selalu dukung aku waktu aku stres. (very colloquial Jakarta-style)

In Jakarta slang, you might hear:

Temen gue selalu dukung gue pas gue stres.
- temen instead of teman
- gue instead of saya/aku
- pas instead of ketika/saat

So:

Use saya in formal writing, with strangers, in polite settings.
Use aku with friends, family, or in relaxed but still fairly standard speech.
Use gue (or other regional forms) only if you’re aiming for local colloquial style and you know it fits the context.

How do we know the tense? Does this mean “always supports” (present) or “always supported” (past)? Indonesian has no tenses, right?

Indonesian verbs don’t change form for tense like English verbs do. mendukung doesn’t tell you whether it’s past, present, or future.

Time information comes from:

Context
Time words like kemarin (yesterday), sudah (already), nanti (later), etc.
Adverbs like selalu (always), sering (often), biasanya (usually), etc.

Your sentence:

Sahabat saya selalu mendukung saya ketika saya stres.

By default, with selalu and no specific time marker, it means something like:

“My friend always supports me when I’m stressed.”
OR
“My friend has always supported me when I was / have been stressed.”

Both readings (habit in the present, or habit over time including the past) are possible. The exact nuance depends on the larger context, not on verb form.

Can I say sedang or merasa here, like “when I am feeling stressed”?

Yes, and it sounds quite natural:

ketika saya sedang stres
- sedang marks an ongoing action/state, similar to English be -ing (am doing, am feeling).
- ketika saya sedang stres = when I am (in the middle of) being stressed / when I am feeling stressed.
ketika saya merasa stres
- merasa = to feel.
- ketika saya merasa stres = when I feel stressed.

All are natural:

ketika saya stres
ketika saya sedang stres
ketika saya merasa stres

Differences are very slight; sedang and merasa just make the “state of feeling” a bit more explicit, closer to the English “am feeling stressed”.