Cuando mi hijo se porta mal, no me gusta regañarlo delante de sus amigas.

Because the verb here is portarse, not just portar.

• portar by itself usually means to carry or to bear, and it is much less common in everyday speech with this meaning.
• portarse means to behave.

So:

• Mi hijo se porta mal = My son behaves badly
• Mi hijo porta... would sound incomplete or like my son carries...

The se is part of the verb, so you need it when talking about behavior.

Portarse mal means to misbehave or to behave badly.

It is a very common expression, especially when talking about children.

Some related examples:

• El niño se porta bien. = The child behaves well.
• Hoy se ha portado fatal. = He behaved terribly today.
• Si te portas mal, no sales. = If you misbehave, you’re not going out.

So in this sentence, cuando mi hijo se porta mal means when my son misbehaves.

Here cuando introduces something that happens habitually or whenever it happens, so Spanish uses the present indicative.

• Cuando mi hijo se porta mal... = When/Whenever my son misbehaves...

This is not talking about one specific future event. It is a general repeated situation.

Compare:

• Cuando mi hijo se porta mal, no me gusta regañarlo...
  = Whenever he misbehaves, I don’t like telling him off...
• Cuando mi hijo se porte mal, hablaré con él.
  = When my son misbehaves / the next time he misbehaves, I’ll talk to him.

In the second one, se porte is subjunctive because it refers to a future event.

Because gustar works differently from English to like.

In Spanish, the thing that is pleasing is the grammatical subject, and the person who feels the liking is shown with an indirect object pronoun:

• me gusta = it is pleasing to me / I like it
• te gusta = you like it
• le gusta = he/she likes it

So:

• No me gusta regañarlo... literally means Telling him off is not pleasing to me
• Natural English: I don’t like telling him off...

The me is necessary because it shows who doesn’t like it.

Because regañar takes a direct object when you tell someone off.

• regañar a alguien = to scold/tell someone off

So:

• regañarlo = to scold him
• regañarla = to scold her
• regañarlos = to scold them

Even though English says tell him off, Spanish treats him as the direct object here.

That is why lo is used, not le.

It is made of:

• regañar = to scold / to tell off
• lo = him

Combined:

• regañar + lo → regañarlo

This is very common with infinitives in Spanish. The object pronoun can be attached directly to the infinitive:

• verlo = to see him/it
• hacerlo = to do it
• decirle = to tell him/her
• regañarlo = to scold him

In this sentence, the most natural form is regañarlo.

With an infinitive, Spanish usually allows the pronoun to attach to the end:

• No me gusta regañarlo...

You generally would not say:

• No me lo gusta regañar ❌

That is wrong because gustar already has its own pronoun structure (me gusta) and lo belongs with regañar, not with gustar.

A separate pronoun before the verb is possible with some verb combinations, but not in this exact structure. Here, attaching it to the infinitive is the standard choice.

Delante de means in front of or, in this context, in front of / in the presence of.

Examples:

• Está delante de la casa. = It is in front of the house.
• No lo digas delante de los niños. = Don’t say it in front of the children.

The de is part of the fixed expression delante de, so you cannot normally drop it.

In this sentence:

• delante de sus amigas = in front of his female friends

It suggests not wanting to embarrass him in front of them.

Sometimes yes, but not always with exactly the same feel.

• delante de is very common for both literal and social situations.
• frente a often means facing, opposite, or in front of, and can sound a bit more physical or spatial.

Here, delante de sus amigas is the most natural choice because it fits the idea of not wanting to scold him in front of other people.

You might hear:

• No me gusta regañarlo delante de sus amigas. = very natural
• No me gusta regañarlo frente a sus amigas. = possible, but less idiomatic here

In this sentence, sus most naturally refers to mi hijo.

So:

• sus amigas = his female friends

Spanish possessives like su/sus can be ambiguous out of context, because they can mean:

• his
• her
• your (formal)
• their

But here the most logical reading is my son’s female friends.

If you wanted to make it extra clear, you could say:

• las amigas de mi hijo

But sus amigas is perfectly normal.

Because amigas specifically means female friends.

• amigas = female friends
• amigos = male friends, or a mixed group of male and female friends

So this sentence is specifically saying that the son is in front of his girl friends rather than just friends in general.

If the group were mixed or unspecified, Spanish would usually use:

• delante de sus amigos

Because possessives like mi, tu, su, nuestro normally replace the article.

So Spanish says:

• sus amigas = his/her/their friends

not:

• las sus amigas ❌

This is the normal pattern:

• mi casa
• tu hermano
• sus amigas

If you want to use an article, the structure changes:

• las amigas de mi hijo

But with sus, no article is used.

Yes, regañar is very common in Spain.

It usually means:

• to scold
• to tell off
• to reprimand

It is stronger than just correcting someone, but not as strong as something like to punish.

So:

• corregir = to correct
• regañar = to scold / tell off
• castigar = to punish

In this sentence, regañarlo suggests verbally telling the son off, not physically punishing him or giving him a formal punishment.

Yes. Spanish can move the clauses around quite naturally.

Original:

• Cuando mi hijo se porta mal, no me gusta regañarlo delante de sus amigas.

You could also say:

• No me gusta regañarlo delante de sus amigas cuando mi hijo se porta mal.

But the original version is more natural because it sets up the situation first:

1. Cuando mi hijo se porta mal
2. no me gusta regañarlo delante de sus amigas

That order is very common in both Spanish and English when introducing a condition or repeated situation.