Μου λείπεις πολύ όταν είσαι στο εξωτερικό.

Because Greek expresses this idea differently.

• Μου λείπεις literally works more like you are missing to me or your absence is felt by me.
• So the person being missed is the subject of the verb: λείπεις = you are absent / you are missed
• The person who feels that absence is shown with μου = to me

So:

• Μου λείπεις = I miss you
• Σου λείπω = You miss me

This is one of the most important things for English speakers to get used to.

Because the subject is you.

In English, we say I miss you, so learners often expect a first-person verb. But in Greek, the structure is reversed:

• λείπεις = you are missing / you are absent
• μου = to me

So the grammar is:

• you = subject
• me = indirect object / experiencer

That is why the verb agrees with you, not with I.

Μου is the weak genitive form of εγώ and here it means to me.

In this sentence, it marks the person who feels the absence.

So:

• μου = to me
• σου = to you
• του / της = to him / her
• μας = to us
• σας = to you (plural/formal)
• τους = to them

With λείπω in this meaning, Greek uses this kind of pronoun, not a direct-object pronoun like με or σε.

No. Λείπω has a broader basic idea connected to absence or lack.

Common uses include:

• Λείπω από το σπίτι. = I am away from home.
• Έλειπε από το μάθημα. = He/She was absent from class.
• Μου λείπεις. = I miss you.

So the connection is: if someone is absent, that absence can be felt by another person.

That is why λείπω can mean both be absent and, in expressions like this, be missed.

Because Greek usually does not need subject pronouns unless you want emphasis or contrast.

The verb ending already tells you the subject:

• λείπεις clearly shows you (singular)
• είσαι clearly shows you (singular)

So εσύ is unnecessary unless you want to stress it:

• Εσύ μου λείπεις πολύ. = You are the one I really miss.

Likewise, εγώ is not used because Greek is not saying I miss in the same grammatical way English does.

Πολύ here means a lot or very much.

It modifies the idea of missing someone:

• Μου λείπεις πολύ. = I miss you a lot.

Its position is natural here, after the verb phrase. This is very common.

You may also hear slightly different word orders depending on emphasis, but Μου λείπεις πολύ is standard and natural.

You can strengthen it too:

• Μου λείπεις πάρα πολύ. = I miss you very, very much.

Because here όταν introduces a repeated or general situation: when / whenever you are abroad.

So όταν είσαι στο εξωτερικό means something like:

• when you are abroad
• whenever you are abroad

The present tense fits that habitual sense very well.

So the whole sentence suggests a recurring feeling, not just one single specific event.

Στο is a contraction of σε + το.

So:

• σε = in / at / to
• το εξωτερικό = literally the exterior / abroad / foreign countries

Together:

• στο εξωτερικό = abroad or in a foreign country / outside the country

This is a very common fixed expression in Greek.

Because Greek often uses το εξωτερικό as a noun meaning foreign countries, overseas, or simply abroad.

It is idiomatic and extremely common.

For example:

• Ζει στο εξωτερικό. = He/She lives abroad.
• Σπουδάζει στο εξωτερικό. = He/She studies abroad.

So even though the literal idea may look unusual to an English speaker, it is the normal Greek expression.

Yes. Greek word order is more flexible than English, though some versions sound more neutral than others.

The original:

• Μου λείπεις πολύ όταν είσαι στο εξωτερικό.

A very natural alternative:

• Όταν είσαι στο εξωτερικό, μου λείπεις πολύ.

Both are correct. The difference is mainly one of focus:

• starting with Μου λείπεις πολύ foregrounds the feeling
• starting with Όταν είσαι στο εξωτερικό foregrounds the situation

Sometimes, yes, but the nuance changes slightly.

• όταν = when
• όποτε = whenever / every time that

So:

• Μου λείπεις πολύ όταν είσαι στο εξωτερικό. = I miss you a lot when you’re abroad.
• Μου λείπεις πολύ όποτε είσαι στο εξωτερικό. = I miss you a lot whenever you’re abroad.

In many contexts, both can work, but όποτε makes the repeated every time sense more explicit.

Yes, but it is not exactly the same in tone or frequency.

• Μου λείπεις is the most natural everyday way to say I miss you
• Σε νοσταλγώ is understandable, but it can sound more literary, emotional, or less conversational depending on context

So for normal modern spoken Greek, Μου λείπεις is usually the best choice.

You would change the verb and pronouns to the plural/formal forms:

• Μου λείπετε πολύ όταν είστε στο εξωτερικό.

This can mean:

• I miss you all a lot when you are abroad
• I miss you a lot when you are abroad (formal singular)

So:

• λείπεις / είσαι = singular informal
• λείπετε / είστε = plural or formal singular