Ik mis mijn vriend zo.

Ik mis is the present tense of the verb missen (to miss).

• ik mis = I miss / I am missing
• ik miste = I missed / I was missing (past tense)

Dutch usually uses the simple present where English might also use a continuous form. So Ik mis mijn vriend zo is a completely natural way to say I miss my boyfriend/friend so much.

In this sentence, zo means something like so much or so badly.

So:

• Ik mis mijn vriend. = I miss my boyfriend/friend.
• Ik mis mijn vriend zo. = I miss my boyfriend/friend so much.

This use of zo is very common in spoken Dutch and sounds emotional and natural.

Dutch often puts short intensifying words like zo toward the end in emotional statements.

So Ik mis mijn vriend zo sounds very natural. It gives the sentence a strong emotional ending.

You could also hear:

• Ik mis mijn vriend zo erg. = I miss my boyfriend/friend so much.
• Ik mis hem zo. = I miss him so much.

Putting zo at the end is normal here.

It can mean either, depending on context.

• vriend = male friend
• vriend can also mean boyfriend

Very often, mijn vriend is understood as my boyfriend, especially in everyday speech. If someone wants to make it clearly platonic, they may use context or say something more specific.

Similarly:

• vriendin can mean female friend or girlfriend

So this is one of those words where context matters a lot.

Mijn is the possessive adjective meaning my.

• mijn vriend = my friend / my boyfriend

A few useful comparisons:

• mijn = my
• vriend = singular (friend / boyfriend)
• vrienden = plural (friends)

So:

• Ik mis mijn vriend = I miss my friend/boyfriend
• Ik mis mijn vrienden = I miss my friends

And mij is not correct here, because mij means me and is an object pronoun, not a possessive word.

No, this is the normal basic Dutch word order for a main clause:

subject + verb + object + extra element

So here:

• Ik = subject
• mis = verb
• mijn vriend = object
• zo = intensifier

That gives:

Ik mis mijn vriend zo.

This is very similar to normal English word order, except that Dutch uses zo in this way at the end.

The infinitive is missen.

Present tense:

• ik mis
• jij mist
• hij/zij mist
• wij missen
• jullie missen
• zij missen

So mis is simply the ik-form of missen.

Yes. That is also very common.

Compare:

• Ik mis mijn vriend zo. = emotional, natural, conversational
• Ik mis mijn vriend heel erg. = very common, clear, slightly more literal
• Ik mis mijn vriend zo erg. = very strong, very natural

All three are correct. The version with zo often sounds especially heartfelt.

Mijn is pronounced roughly like mine in English, though the Dutch ij sound is not exactly the same.

A rough guide:

• mijn ≈ mine
• vriend has a long ee sound, like vreet but with a Dutch v/r

If you are learning pronunciation, the main thing to remember is that ij in Dutch is a very common vowel combination and often sounds somewhat like English eye or mine, depending on accent.

Yes. You can say:

• Ik mis hem zo. = I miss him so much.

That sounds very natural if it is already clear who you are talking about.

So:

• Ik mis mijn vriend zo.
• Ik mis hem zo.

Both are correct; the second is just less explicit.