Я довіряю своїй подрузі, і вона довіряє мені навіть у складні дні.

Because довіряти takes the dative case in Ukrainian.

So:

• подруга → подрузі = to a friend / to my friend
• я → мені = to me

This is different from English, where trust takes a direct object: I trust my friend. In Ukrainian, the structure is closer to I give trust to my friend.

So:

• Я довіряю своїй подрузі = I trust my friend
• вона довіряє мені = she trusts me

Ukrainian usually uses свій when the possessor is the subject of the same clause.

So in Я довіряю своїй подрузі:

• the subject is Я
• the friend belongs to me
• therefore Ukrainian prefers свій

This is very common:

• Я люблю свою родину = I love my family
• Вона взяла свою сумку = She took her bag

Using моїй is not impossible in some contexts, but своїй is the normal and most natural choice here.

Своїй is the dative singular feminine form of свій.

It agrees with подрузі, which is:

• feminine
• singular
• dative

So both words match:

• своїй = dative singular feminine
• подрузі = dative singular feminine

That is why the phrase is своїй подрузі.

Подруга is the dictionary form, called the nominative singular.

After довіряти, you need the dative singular, so подруга changes to подрузі.

This is a normal pattern for many feminine nouns:

• книга → книзі
• сестра → сестрі
• подруга → подрузі

So своїй подрузі means to my friend.

For the same reason: довіряти requires the dative case.

The pronoun я changes like this:

• я = I
• мене = me (accusative/genitive, depending on context)
• мені = to me

Since довіряти needs dative, you get:

• вона довіряє мені = she trusts me

Yes, Ukrainian often drops subject pronouns when they are clear from the verb ending.

So this sentence could also be:

• Я довіряю своїй подрузі, і довіряє мені навіть у складні дні.

But that version sounds incomplete or awkward because the second clause benefits from having its own subject stated clearly. A more natural reduced version would be possible only in certain contexts, but here вона helps by:

• making the second subject explicit
• creating a nice contrast: I trust her, and she trusts me
• sounding balanced

So вона is not strictly necessary in every sentence, but here it is very natural and useful.

Because і is joining two independent clauses:

1. Я довіряю своїй подрузі
2. вона довіряє мені навіть у складні дні

Each part has its own subject and verb, so a comma is standard here.

Compare:

• Я довіряю своїй подрузі, і вона довіряє мені.
  Two clauses → comma

But:

• Я довіряю подрузі і поважаю її.
  One subject, two verbs → usually no comma

Навіть means even.

It adds emphasis. In this sentence, it suggests that her trust continues even under difficult circumstances.

So the idea is not just:

• she trusts me

but more strongly:

• she trusts me even on difficult days

It highlights loyalty or emotional support.

Here у складні дні is a time expression meaning something like:

• on difficult days
• during difficult days

In this kind of expression, Ukrainian commonly uses у/в + accusative.

So:

• складні дні = accusative plural
• у складні дні = on/during difficult days

The form у складних днях is locative plural, but it would not sound natural for this meaning here.

Both words are plural:

• день = day
• дні = days

And the adjective must agree with the noun in:

• number
• gender where relevant
• case

So:

• складні matches дні
• both are plural
• both are in the accusative here

This kind of agreement is a basic feature of Ukrainian grammar.

It is present tense, but like the English present simple, it can describe:

• what is happening now
• a general truth
• a habitual or ongoing relationship

In this sentence, it most naturally expresses a general ongoing state:

• I trust my friend
• she trusts me

So it is not just about one single moment. It describes the relationship more broadly.

Yes. Ukrainian word order is fairly flexible, and changing it usually changes emphasis, not the core meaning.

For example:

• Я довіряю своїй подрузі, і вона довіряє мені навіть у складні дні.
  Neutral, natural order.

• Своїй подрузі я довіряю, і вона довіряє мені навіть у складні дні.
  Emphasizes my friend.

• Навіть у складні дні вона довіряє мені.
  Emphasizes even on difficult days.

So the original sentence is a neutral, standard version.

Because Ukrainian has no articles.

English says:

• I trust my friend

with no article because my already specifies the noun.

But even when English would use a or the, Ukrainian usually just relies on context, word order, and sometimes other words to show the meaning.

So подрузі simply means friend in the grammatical form needed, and context tells you whether it is a friend, the friend, or my friend.