Damatlığı dar bulduğu için terziye götürdü; yarın son kez deneyecek.

Damatlık is a clothing word, not a person. It means the groom’s outfit, often the groom’s suit/tuxedo.

It comes from damat = groom.
So damatlık is basically something for the groom to wear.

Here, damatlığı is most naturally damatlık + -(y)ı, the definite accusative form: the groom’s suit/outfit as a specific object.

Two things happen:

• damatlık
  • -ı → damatlığı
• the final k softens to ğ before a vowel

So:

• damatlık = groom’s suit / tuxedo
• damatlığı = the groom’s suit / tuxedo as a definite object

A useful note: this form can also be ambiguous in other contexts, because it can look like a 3rd-person possessed form too. But in this sentence, learners will usually understand it simply as the specific outfit being discussed.

Very literally, it means something like:

because he/she found it tight

Breakdown:

• dar = narrow, tight
• bulduğu = that he/she found
• için = because / due to

So damatlığı dar bulduğu için means:

because he found the groom’s suit too tight

In Turkish, bulmak is often used like to find something [adjective].

So:

• pahalı bulmak = to find expensive
• uygun bulmak = to find suitable
• zor bulmak = to find difficult
• dar bulmak = to find tight / too tight

This is a very common Turkish pattern.
So damatlığı dar buldu means he found the suit tight.

This is a very good question, because the meaning changes slightly.

• dar olduğu için = because it was tight
• dar bulduğu için = because he found it tight

So:

• dar olduğu için sounds more objective: the suit was tight
• dar bulduğu için includes the person’s judgment/experience: he considered it tight

In English, both may end up translated similarly, but Turkish is making a small distinction here.

Bulduğu comes from bulmak and uses the -DIK subordinating/nominalizing structure.

Very roughly:

• bul- = verb stem
• -duk/-dık/-dük/-dik = a subordinating ending
• -u = 3rd person possessive/agreement ending

So bulduğu is not just a simple past tense verb like buldu.
It is part of a dependent clause: the fact that he found..., what he found..., or here, with için, because he found...

This is a very common Turkish pattern:

• geldiği için = because he came
• yorgun olduğu için = because he is/was tired
• beğenmediği için = because he didn’t like it

Here, için means because of / because.

It attaches to the whole preceding clause:

• damatlığı dar bulduğu için = because he found the groom’s suit tight

So in this sentence, için introduces the reason for taking it to the tailor.

Because -ye / -ya here is the dative case, often meaning to.

• terzi = tailor
• terziye = to the tailor

Since the action is taking something to someone/somewhere, Turkish uses the dative:

• okula götürmek = to take to school
• doktora götürmek = to take to the doctor
• terziye götürmek = to take to the tailor

The understood object is the suit/outfit.

So the full idea is:

He took it to the tailor.

Turkish often leaves out objects when they are already clear from context. Repeating damatlığı again would be possible in some contexts, but it is often unnecessary.

So:

• Damatlığı dar bulduğu için terziye götürdü
  = Because he found the suit tight, he took it to the tailor

The it is understood.

The subject is understood as he/she, probably he in context, but Turkish often drops subject pronouns when they are obvious.

That is very normal in Turkish.

• götürdü = he/she took
• deneyecek = he/she will try on

Turkish does not need to say o unless there is a reason to emphasize or clarify it.

So the sentence naturally leaves the subject unstated.

Son kez means for the last time or one last time.

• son = last
• kez = time / occasion

So:

• yarın son kez deneyecek = he will try it on one last time tomorrow

Very common expressions:

• bir kez = once
• iki kez = twice / two times
• son kez = for the last time

The verb denemek basically means to try. In clothing contexts, it commonly means to try on.

So:

• elbise denemek = to try on a dress
• ceket denemek = to try on a jacket

In this sentence, the object is omitted because it is obvious. The meaning is:

He will try it on tomorrow one last time.

Because the sentence mentions a tailor, this is clearly about a fitting.

Because the sentence describes two different times:

• götürdü = took → already happened
• deneyecek = will try on → will happen tomorrow

So the timeline is:

1. He found the suit tight.
2. He took it to the tailor.
3. Tomorrow he will try it on one last time.

This is completely natural in Turkish.

The semicolon links two closely related parts:

• He took it to the tailor
• tomorrow he’ll try it on one last time

It shows a pause stronger than a comma but weaker than a full stop.
It is mainly a punctuation choice, not a special grammar rule.

You could also see similar ideas written with a period in everyday writing.