Если ты обиделся, нам лучше объясниться сегодня вечером.

In Russian, обидеться often means to take offense / to become offended, so the past tense обиделся literally means got offended or took offense.

That is why Если ты обиделся is often very natural in situations where English might say if you’re offended. Russian is focusing on the change of state: you were fine, then something upset you.

So this part is not strange at all:

• Если ты обиделся = If you got offended / if you took offense / if you’re upset

The basic verb is обидеться, which is a reflexive verb. Here it means to take offense, to get hurt/offended.

Compare:

• обидеть = to offend someone
• обидеться = to become offended / to take offense

So:

• Я тебя обидел = I offended you
• Ты обиделся = You got offended

The -ся changes the meaning of the verb, so it is an important part of the word, not something optional.

Russian past tense verbs agree with gender in the singular.

• обиделся = masculine
• обиделась = feminine
• обиделось = neuter
• обиделись = plural

So this sentence is addressed to a man or boy:

• Если ты обиделся...

If you were speaking to a woman or girl, it would be:

• Если ты обиделась, нам лучше объясниться сегодня вечером.

This is a very common Russian pattern:

• кому + лучше + infinitive

Literally, нам лучше объясниться means something like it is better for us to talk things through.

Here:

• нам = dative case of мы
• лучше = better
• объясниться = to explain ourselves / talk things through

So нам лучше does not mean we are better. It means it would be better for us.

Similar examples:

• Тебе лучше уйти. = You’d better leave.
• Нам лучше подождать. = We’d better wait.

Объясниться is not just to explain in the simple sense. In this context it usually means:

• to talk things through
• to clear the air
• to explain oneself to each other
• to have an honest conversation

So нам лучше объясниться suggests that there is tension, misunderstanding, or hurt feelings, and it would be good to discuss them openly.

This is different from:

• объяснить = to explain something
• объясниться = to explain oneself / sort things out in conversation

The verb объясниться has its own meaning as a reflexive verb. It does not simply mean explain oneself to oneself in a literal sense. Reflexive verbs in Russian often develop special meanings.

Here объясниться means something like:

• to have an explanation with someone
• to clear things up
• to talk openly and settle the matter

So the -ся is part of the dictionary form of the verb and must be learned together with it.

Because Russian often uses лучше in an impersonal recommendation structure:

• лучше + infinitive
• кому-то лучше + infinitive

Examples:

• Лучше не спорить. = It’s better not to argue.
• Тебе лучше остаться. = You’d better stay.
• Нам лучше объясниться. = We’d better talk things through.

So the infinitive объясниться is exactly what you would expect after лучше.

Yes. Russian often allows то after an если clause, but it is optional in many sentences.

So you could say:

• Если ты обиделся, нам лучше объясниться сегодня вечером.
• Если ты обиделся, то нам лучше объясниться сегодня вечером.

Both are correct.

Adding то can make the structure feel a little more explicit: if X, then Y. Without то, the sentence sounds slightly more natural and streamlined in everyday speech.

Вечером is the instrumental case.

Russian often uses the instrumental without a preposition to express time when something happens, especially with parts of the day:

• утром = in the morning
• днём = in the daytime / during the day
• вечером = in the evening
• ночью = at night

So:

• сегодня вечером = this evening / tonight

This is a set pattern and very common.

Сегодня вечером is completely natural and means this evening / tonight.

Other possible phrases, depending on context, include:

• сегодня ночью = tonight, later at night
• вечером = in the evening
• сегодня = today

But сегодня вечером is a good, clear choice because it specifies when the conversation should happen.

It is stronger than a casual we should talk, but usually softer than a direct command.

Possible English equivalents are:

• We’d better talk things through
• We should clear this up
• It would be better for us to talk this out

So the phrase suggests:

1. there is a problem or tension,
2. talking is necessary,
3. doing it sooner is a good idea.

It has a practical, slightly serious tone.

No, Russian word order is fairly flexible, though some versions sound more natural than others.

The original:

• Если ты обиделся, нам лучше объясниться сегодня вечером.

Possible variations:

• Если ты обиделся, сегодня вечером нам лучше объясниться.
• Нам лучше объясниться сегодня вечером, если ты обиделся.

The original version is very natural. It first gives the condition, then the recommendation, then the time.

Changing word order usually changes emphasis more than basic meaning.

It is informal because it uses ты.

If you were addressing someone formally, you would use вы, and the sentence would change accordingly:

• Если вы обиделись, нам лучше объясниться сегодня вечером.

So the original sentence sounds like something said to a friend, partner, relative, or someone you know well.