Я доволен, что ты пришёл вовремя.

In the present tense, Russian usually leaves out the verb быть (to be).

So Я доволен literally looks like I satisfied/pleased, but it actually means I am satisfied / I am pleased.

This is normal Russian:

• Я доволен = I am pleased
• Ты дома = You are at home
• Она врач = She is a doctor

Using есть here would usually sound unnatural in modern Russian.

Доволен is the short form of the adjective довольный.

In Russian, short-form adjectives are commonly used after an implied to be to describe a current state:

• Я доволен = I am pleased/satisfied

The full form довольный is more commonly used before a noun:

• довольный студент = a satisfied student

So in this sentence, доволен is the natural form.

Yes. It agrees with the speaker in gender and number.

Forms:

• masculine: доволен
• feminine: довольна
• neuter: довольно
• plural: довольны

So:

• a man says: Я доволен
• a woman says: Я довольна

In your sentence, доволен tells us the speaker is male.

Nothing is wrong here. Russian can say both:

• Я доволен, что ты пришёл вовремя.
• Я доволен тем, что ты пришёл вовремя.

The version with тем is a little more explicit and sometimes a bit more formal or bookish. The shorter version without тем is very common in everyday speech.

This happens because доволен often connects either:

• to a noun/pronoun in the instrumental case: Я доволен тобой
• or to a clause: Я доволен, что...

Here что means that and introduces a subordinate clause:

• Я доволен, что ты пришёл вовремя.
• I’m pleased that you came on time.

You would not normally use чтобы here.

Чтобы usually means something like so that, in order that, or introduces something desired:

• Я хочу, чтобы ты пришёл вовремя. = I want you to come on time.

So:

• что = a fact is being stated
• чтобы = a wish, goal, or desired action

Because Russian past tense agrees with the subject in gender and number.

Here the subject is ты, and пришёл shows that the person being addressed is male.

Compare:

• ты пришёл = you came (to a man)
• ты пришла = you came (to a woman)
• вы пришли = you came (plural or polite singular)

So in this sentence:

• доволен describes the speaker and is masculine
• пришёл describes ты and is also masculine

Those are two separate agreements.

The infinitive is прийти = to come / to arrive.

This verb is a little irregular, so the forms do not look exactly like the infinitive:

• infinitive: прийти
• past masculine: пришёл
• past feminine: пришла
• past plural: пришли

This is a very common verb, so it is worth memorizing as its own pattern.

Because пришёл is perfective, and it presents the action as a completed event: the person arrived, and the result matters.

That fits вовремя very well:

• пришёл вовремя = arrived on time

Приходил is imperfective and would usually suggest a different viewpoint, such as repeated action, process, or just the fact of having come in some broader sense. In this sentence, for one completed arrival, пришёл is the natural choice.

Because что ты пришёл вовремя is a subordinate clause, and Russian normally separates subordinate clauses with a comma.

So the structure is:

• main clause: Я доволен
• subordinate clause: что ты пришёл вовремя

That is why the comma is required:

• Я доволен, что ты пришёл вовремя.

Вовремя is an adverb meaning on time, in time, or at the right moment, depending on context.

In this sentence, it means:

• on time
• punctually

It is written as one word: вовремя.

Examples:

• Он пришёл вовремя. = He came on time.
• Ты позвонил вовремя. = You called at the right moment / just in time.

Yes. Я рад, что ты пришёл вовремя is also very natural.

The nuance is slightly different:

• рад = glad, happy
• доволен = pleased, satisfied, content

So:

• Я рад, что ты пришёл вовремя sounds a bit more emotional
• Я доволен, что ты пришёл вовремя sounds a bit more like approval or satisfaction

Both are correct; they just feel a little different.

You change the verb пришёл to match the person being addressed.

To a woman:

• Я доволен, что ты пришла вовремя.
• If the speaker is a woman: Я довольна, что ты пришла вовремя.

To you plural or polite singular:

• Я доволен, что вы пришли вовремя.
• If the speaker is a woman: Я довольна, что вы пришли вовремя.

So remember:

• доволен / довольна agrees with I
• пришёл / пришла / пришли agrees with you

The main stress points are:

• Я дово́лен, что ты пришёл вовре́мя.

A few notes:

• дово́лен: stress on -во́-
• пришёл: stress on ё; ё is always stressed
• вовре́мя: stress on -вре́-

That stress pattern is important, especially in пришёл, because the ё should not be pronounced like an unstressed е.