Divento nervosa se la discussione dura troppo a lungo.

In Italian, subject pronouns are often omitted because the verb ending already shows who the subject is.

• divento = I become / I get
• The -o ending tells you the subject is I

So Divento nervosa is completely natural. You could say Io divento nervosa, but adding io usually gives extra emphasis, like I get nervous.

Divento is the 1st person singular present tense of diventare.

Here, it means:

• I become
• or more naturally in English, I get

So Divento nervosa is literally I become nervous, but in natural English it is often I get nervous.

Nervosa agrees with the speaker’s gender.

• nervoso = masculine singular
• nervosa = feminine singular

So this sentence is being said by a female speaker.
A male speaker would say:

• Divento nervoso se la discussione dura troppo a lungo.

There is a difference in meaning:

• sono nervosa = I am nervous
• divento nervosa = I become / get nervous

So divento focuses on the change of state. It means the discussion causes the speaker to become nervous, not that she is already nervous from the start.

Se means if.

In this sentence, both verbs are in the present tense:

• Divento nervosa
• se la discussione dura troppo a lungo

This is very common in Italian for general truths, habits, or repeated situations:

• If the discussion goes on too long, I get nervous.

Italian often uses the present tense in both parts where English also often uses the present.

Dura is the 3rd person singular present tense of durare, meaning to last.

Because the subject is la discussione (singular), the verb is singular too:

• la discussione dura = the discussion lasts

If the subject were plural, the verb would change:

• le discussioni durano = the discussions last

Italian uses durare to express that something lasts for a certain amount of time.

So:

• La discussione dura troppo a lungo = The discussion lasts too long

This is the normal way to say it.
Italian does not usually express this idea with essere in the same way English sometimes rephrases things.

Troppo a lungo means too long or more literally for too long.

Breakdown:

• troppo = too / excessively
• a lungo = for a long time / long

Together they express excess duration:

• dura troppo a lungo = lasts too long

You need both because:

• a lungo gives the idea of duration
• troppo adds the idea that the duration is excessive

Here, a lungo is an adverbial expression meaning:

• for a long time
• for long

In this sentence, it works with durare:

• durare a lungo = to last a long time

By itself, lungo is usually an adjective meaning long:

• un discorso lungo = a long speech
• una lunga discussione = a long discussion

So:

• una discussione lunga describes the discussion
• la discussione dura a lungo describes how long it lasts

Yes, the se clause can come first or second.

Both are correct:

• Divento nervosa se la discussione dura troppo a lungo.
• Se la discussione dura troppo a lungo, divento nervosa.

The meaning stays the same.
Putting se la discussione... first can make the condition feel slightly more prominent, but both orders are very natural.

Usually, this sentence sounds like a general or repeated situation:

• I get nervous if the discussion goes on too long.

So it is not just about one specific discussion happening right now. It describes what typically happens.

Italian present tense often covers:

• present actions
• habits
• general truths
• repeated reactions

Context would tell you whether it refers to a specific situation or a general pattern.

Yes, but the meaning changes slightly.

• discussione can mean discussion, and sometimes also argument, depending on context
• conversazione = conversation, usually more neutral
• litigio = quarrel / fight, clearly more negative

So:

• Divento nervosa se la discussione dura troppo a lungo can suggest either a long discussion or a long argument, depending on context.
• Divento nervosa se il litigio dura troppo a lungo is stronger and clearly means a quarrel/fight.
• Divento nervosa se la conversazione dura troppo a lungo is more neutral.

No. This sentence is in the first person singular, so formality toward another person does not affect the grammar here.

The only likely change would be the speaker’s gender:

• Divento nervosa if the speaker is female
• Divento nervoso if the speaker is male

Otherwise, the sentence stays the same.