Bu kavganın asıl sebebi yorgunluk olabilir.

Because kavganın is the genitive form of kavga.

In this sentence, bu kavganın asıl sebebi means something like the main reason of/for this argument. Turkish often uses a genitive + possessed noun structure for this kind of relationship.

• kavga = argument, fight
• kavganın = of the argument / the argument’s

The genitive ending is -(n)ın / -(n)in / -(n)un / -(n)ün, depending on vowel harmony.

Here:

• base noun: kavga
• last vowel: a
• so the genitive ending becomes -nın
• result: kavganın

The n appears because the noun ends in a vowel.

Because in this kind of noun phrase, the second noun takes a possessive ending.

The pattern is:

• first noun in the genitive
• second noun with a 3rd-person possessive suffix

So:

• kavganın = of the argument
• sebebi = its reason / the reason

Together:

• kavganın sebebi = the argument’s reason = the reason for the argument

Why sebebi?

• base noun: sebep = reason
• possessive suffix: -(s)ı / -(s)i / -(s)u / -(s)ü
• because sebep ends in a consonant, you add just -i
• p changes to b before the vowel, so:
  • sebep + i → sebebi

This is a very common sound change in Turkish.

It is a genitive-possessive noun phrase.

You can break it down like this:

• bu = this
• kavganın = of this argument
• asıl = main, real, actual
• sebebi = reason

So the structure is:

• bu kavganın = of this argument
• asıl sebebi = its main reason

Together:

• bu kavganın asıl sebebi = the main reason for this argument

This structure is extremely common in Turkish:

• evin kapısı = the door of the house
• filmin sonu = the end of the film
• sorunun cevabı = the answer to the question

English often uses of or for, but Turkish uses this noun-linking pattern instead.

Because asıl is an adjective, and Turkish adjectives normally come before the noun they describe.

So:

• asıl sebep = the main reason
• asıl sebebi = its main reason

This is similar to English word order:

• main reason
• not reason main

Other examples:

• büyük ev = big house
• güzel film = beautiful film
• önemli konu = important topic

So asıl simply follows the normal adjective + noun order.

Because yorgunluk means tiredness / fatigue, which is a noun, while yorgun means tired, which is usually an adjective.

Here the sentence is saying that the main reason may be tiredness/fatigue, so a noun is needed.

• yorgun = tired
• yorgunluk = tiredness, fatigue

The ending -luk / -lık / -lik / -lük often turns adjectives or other words into nouns:

• yorgun → yorgunluk = tiredness
• aç → açlık = hunger
• genç → gençlik = youth

So yorgunluk is the natural word here.

Here olabilir means may be, might be, or could be.

It expresses possibility, not certainty.

It comes from:

• ol- = to be / become / happen
• -abil- = can, may, be able to
• -ir = aorist ending

So literally it is something like it can be, but in real usage it often means:

• maybe it is
• it may be
• it could be

In this sentence:

• Bu kavganın asıl sebebi yorgunluk olabilir.
• = The main reason for this argument may be fatigue.

So the speaker is making a guess or a cautious suggestion.

In this sentence, it is about possibility.

The suffix -abil- can express either:

1. ability

   • Yüzebilir. = He/She can swim.

2. possibility

   • Evde olabilir. = He/She may be at home.

Here, since the subject is not a person doing an action, the meaning is clearly possibility:

• yorgunluk olabilir = it may be fatigue

So this is not able to be in the physical sense. It is might be.

Because it is being used as the predicate noun of the sentence.

In English, this is the part after is / may be:

• The reason may be fatigue.

In Turkish, predicate nouns often appear in the bare form, with no extra case ending:

• O öğretmen. = He/She is a teacher.
• Sorun para. = The problem is money.
• Sebep yorgunluk olabilir. = The reason may be fatigue.

So yorgunluk does not need accusative, dative, or another case here. It is simply naming what the reason may be.

Because Turkish normally places the finite verb near the end, often at the very end.

So the structure here is:

• Bu kavganın asıl sebebi = topic / subject-like part
• yorgunluk = complement
• olabilir = verb

This end position is very typical in Turkish:

• Ben okula gidiyorum. = I am going to school.
• Bu çok önemli. = This is very important.
• Sorunun cevabı burada olabilir. = The answer to the question may be here.

English speakers often expect the verb earlier, but Turkish usually saves it for the end.

Yes, Turkish word order is somewhat flexible, but changing it usually changes the focus or emphasis.

The original sentence is neutral and natural:

• Bu kavganın asıl sebebi yorgunluk olabilir.

If you move words around, the sentence may still be grammatical, but it may sound more marked or emphasize something different.

For example:

• Yorgunluk bu kavganın asıl sebebi olabilir.
  • This puts more focus on yorgunluk.

The original version is probably the most natural choice if you are simply stating a possibility.

So yes, word order can change, but the given sentence is a very standard, neutral order.

Because bu directly modifies kavga:

• bu kavga = this argument
• bu kavganın = of this argument

You only need one demonstrative here. Turkish commonly puts bu, şu, or o directly before the noun:

• bu ev = this house
• bu evin kapısı = the door of this house
• bu sorunun cevabı = the answer to this question

So:

• bu kavganın sebebi = the reason for this argument

That is the normal and simplest way to say it.

Yes, literally it is something like the fight’s reason or the reason of the fight, but that is just how Turkish links nouns.

English often prefers:

• the reason for the fight
• the cause of the argument

Turkish commonly uses the genitive-possessive pattern where English might use for, of, or another preposition.

So even if the most literal translation sounds awkward in English, the Turkish structure is completely normal:

• kavganın sebebi = the reason for the argument
• filmin konusu = the subject/topic of the film
• çocuğun adı = the child’s name / the name of the child

So this is a place where you should think in Turkish structure, not word-for-word English.

Yes. This is a very common Turkish consonant change.

The word is:

• sebep = reason

When a vowel-initial ending is added, the final p often changes to b:

• sebep → sebebi

This also happens with other words:

• kitap → kitabı
• ağaç → ağacı
• renk → rengi

So if a dictionary form ends in p, ç, t, k, it may change when a vowel-starting suffix is attached. Learners see this all the time, so it is worth getting used to early.