Í nóvember er ég oft þreyttur, en í desember hittumst við ekki bara oftar, heldur sitjum við líka lengur saman.

Because Icelandic usually uses the preposition í for months when it means in a certain month.

• í nóvember = in November
• í desember = in December

After í in this kind of time expression, the month is in the dative case. For these borrowed month names, the form often looks the same as the basic dictionary form, so you do not see a visible change here.

This is very common in Icelandic:

• í janúar
• í febrúar
• í mars

So this part is a normal time expression.

Because þreyttur is an adjective agreeing with ég = I, and the form chosen depends on the speaker’s gender.

Here, þreyttur is:

• masculine
• singular
• nominative

So the sentence sounds like it is being said by a male speaker.

If a female speaker said it, it would usually be:

• Ég er oft þreytt í nóvember.

A neuter form þreytt is not normally used for a person in this kind of sentence.

Hittumst is the 1st person plural present tense of hittast, which means to meet each other or to meet up.

So:

• við hittumst = we meet / we meet each other

The ending -st is important. It shows that this is the middle voice form, which often gives a reflexive or reciprocal meaning.

Compare:

• hitta = meet / find / hit someone
• hittast = meet each other

So hittumst við means we meet in the sense of we get together / see each other.

Because Icelandic follows the verb-second rule very often in main clauses.

The clause begins with the time expression:

• í desember

Once that element is placed first, the finite verb usually comes next:

• Í desember hittumst við ...

So the order is:

1. fronted element: Í desember
2. verb: hittumst
3. subject: við

If you did not front í desember, you could say:

• Við hittumst ekki bara oftar ...

Both are grammatical, but the sentence you were given emphasizes in December by putting it first.

This is a very common Icelandic pattern meaning not only ..., but also ...

In the sentence:

• ekki bara oftar, heldur ... líka lengur saman

the structure is:

• ekki bara = not only
• heldur = but rather / but
• líka = also

So Icelandic often uses:

• ekki bara X, heldur Y líka

This is very close to English not only X, but also Y.

A few examples:

• Hann er ekki bara klár, heldur líka skemmtilegur.

  • He is not only smart, but also funny.

• Við borðum ekki bara meira, heldur líka seinna.

  • We not only eat more, but also later.

Because they are comparing December with November, or at least contrasting one situation with another.

• oft = often

• oftar = more often

• lengi = for a long time
• lengur = longer

So:

• hittumst við ekki bara oftar = we meet not only more often
• sitjum við líka lengur saman = we also sit together longer

Even if English sometimes uses a slightly different phrasing, Icelandic naturally uses the comparative here because the sentence sets up a contrast:

• in November: one situation
• in December: more frequent and longer meetings

For the same verb-second reason as in hittumst við.

After heldur, the clause begins with the verb:

• heldur sitjum við líka lengur saman

The finite verb sitjum comes before the subject við.

This is normal Icelandic word order in many main clauses, especially after a linking word like heldur in this structure.

So the sentence keeps the same pattern:

• ... hittumst við ...
• ... heldur sitjum við ...

Saman means together.

So:

• sitjum við líka lengur saman = we also sit together for longer

Without saman, the sentence would still make grammatical sense, but it would lose the idea that the people are spending that time with each other.

It helps make the social meaning clearer:

• not only do we meet more often
• we also stay together longer when we do

Yes. Icelandic often uses sitja very naturally in contexts where English might prefer something broader like stay, hang out, or sit and talk.

So sitjum ... lengur saman literally means we sit together longer, but in context it often suggests:

• we remain together longer
• we spend longer sitting and talking
• we stay together longer

This is one of those places where a very literal translation sounds slightly narrower in English than the Icelandic original feels.

Because the first clause simply states a habit or repeated situation:

• er ég oft þreyttur
• I am often tired

That is just the basic adverb oft = often.

In the second part, the sentence is making a comparison:

• hittumst við ... oftar
• we meet more often

So it needs the comparative form oftar.

This is similar to English:

• I am often tired
• We meet more often in December

Yes, those forms are possible in other word orders, but the given sentence follows a very natural Icelandic pattern with fronting and verb-second order.

For example, you could say:

• Við hittumst ekki bara oftar í desember, heldur sitjum við líka lengur saman.

That is also grammatical, but it shifts the emphasis a bit.

The original sentence puts strong focus on the time phrases:

• Í nóvember ...
• í desember ...

This makes the contrast between the two months especially clear.

Yes: it is built as a contrast between two time periods.

Structure:

1. Í nóvember
   • statement about the speaker
2. en í desember
   • contrasting statement about we
3. inside that second part, another paired contrast:
   • ekki bara oftar
   • heldur ... líka lengur saman

So the sentence is doing two things at once:

• contrasting November with December
• saying not only A, but also B

That layered structure is very common in natural Icelandic and is worth learning as a pattern, not just as one sentence.