L'absence de Marie rend Paul triste.

In French, nouns usually need an article more often than they do in English. Here, absence is a feminine singular noun, so the basic form is la absence. But French avoids la before a vowel sound, so it contracts to l'absence.

So:

• la absence → l'absence

This is called elision.

De Marie means of Marie or Marie's.

French often uses de where English uses 's:

• l'absence de Marie = Marie's absence
• le livre de Paul = Paul's book

So this is a very normal French way to show possession or relationship between two nouns.

French does not use the English 's possession pattern. Instead, it usually uses:

• noun + de + person/thing

So English Marie's absence becomes French l'absence de Marie.

This is one of the most common structural differences between English and French.

Rend is the 3rd person singular form of the verb rendre.

In this sentence, rendre means to make or to render in the sense of causing someone to be in a certain state.

So the pattern is:

• X rend Y triste = X makes Y sad

Here:

• L'absence de Marie = the thing causing the emotion
• rend = makes
• Paul = the person affected
• triste = the resulting state

Because French usually follows this order with rendre:

• subject + rendre + person/thing affected + adjective

So:

• L'absence de Marie rend Paul triste

That is the normal order.

Compare:

• Cette nouvelle rend Marie heureuse.
• Le bruit rend les enfants nerveux.

The adjective comes after the person or thing being affected.

Because Paul is the direct object of rend in this construction.

The structure is:

• subject: L'absence de Marie
• verb: rend
• object: Paul
• adjective/complement: triste

So literally the grammar is something like:

• Marie's absence makes Paul sad

French keeps the same basic logic here.

Because triste is an adjective, and it describes Paul's state.

• triste = sad
• tristement = sadly

In this sentence, we are not saying Paul does something sadly. We are saying that the absence makes Paul sad. So an adjective is needed, not an adverb.

Yes, it does agree with Paul, but in this case you do not see any change.

Triste is one of those adjectives whose masculine singular and feminine singular forms are spelled the same:

• masculine singular: triste
• feminine singular: triste

So with Paul or Marie, it would still look the same in the singular:

• L'absence de Marie rend Paul triste.
• L'absence de Paul rend Marie triste.

But in the plural, you would see a difference:

• L'absence de Marie rend Paul et Jean tristes.

Because Marie is a proper name, and proper names in French normally do not take an article in this kind of sentence.

So:

• de Marie = of Marie

Not:

• de la Marie in standard French

French does use articles with some place names or in special cases, but personal names usually appear without one.

Yes. That is also correct.

• L'absence de Marie rend Paul triste = Marie's absence makes Paul sad
• L'absence de Marie attriste Paul = Marie's absence saddens Paul

The second version is a bit more compact because attrister already includes the idea of making someone sad. Both are natural, though attrister can sound slightly more literary or formal depending on context.

Paul est triste just says Paul is sad. It states his condition.

L'absence de Marie rend Paul triste does more than that: it also tells you what causes his sadness.

So:

• Paul est triste. = Paul is sad.
• L'absence de Marie rend Paul triste. = Marie's absence makes Paul sad.

The second sentence gives both the emotion and the reason.

A careful pronunciation would be roughly:

• Lan-sahns duh ma-ree rahn pol treest

A few useful notes:

• L'absence begins with the l' linked directly to absence
• de is usually a light duh sound
• rend has a nasal vowel; the d is not strongly pronounced at the end
• Paul sounds like Pol
• triste ends with a clear st sound

You may also hear smooth linking in natural speech, but there is no required liaison after rend here.

The subject is L'absence de Marie.

That whole noun phrase acts as one unit:

• L'absence = the absence
• de Marie = of Marie

So the thing doing the action of rend is not Marie, but Marie's absence.

That is why the verb is singular:

• L'absence de Marie rend...

not

• rendent