Learn Hardcore Polish: On jest trochę zazdrosny o mojego przyjaciela.

You can sometimes hear On trochę zazdrosny in very colloquial speech, but it sounds more like a short, telegraphic comment or spoken emphasis, not a neutral full sentence.

More natural options are:

On jest trochę zazdrosny o mojego przyjaciela. – neutral.
Jest trochę zazdrosny o mojego przyjaciela. – also very natural; dropping on is fine when it’s clear who you’re talking about.

So:

Dropping on = often OK.
Dropping jest = possible in casual speech, but less standard; keep jest in learner Polish.

Why is it zazdrosny o and not some other preposition (like na)?

The adjective zazdrosny simply takes the preposition o in Polish:

zazdrosny o kogoś / o coś – jealous of someone / of something

This is just how the language works; you have to memorize it as a fixed pattern, like “afraid of” in English.

Compare with other emotion-preposition patterns:

zły na kogoś – angry at someone
dumny z kogoś – proud of someone
pewny czegoś – sure of something

So with zazdrosny, the correct pattern is:

zazdrosny o + [accusative]

Why is it mojego przyjaciela and not mój przyjaciel?

Because of the preposition o.

o in this meaning (“about / over / of” in jealousy) requires the accusative case.
mój przyjaciel is nominative (dictionary form).
In the accusative, for a masculine animate noun like przyjaciel, the endings change:
- mój → mojego
- przyjaciel → przyjaciela

So:

Nominative (subject): Mój przyjaciel jest miły. – My friend is nice.
Accusative (after o here): On jest zazdrosny o mojego przyjaciela.

Masculine animate accusative looks like the genitive, which is why you see -ego and -a.

Can trochę go in another place in the sentence?

The most natural positions are:

On jest trochę zazdrosny o mojego przyjaciela.
On trochę jest zazdrosny o mojego przyjaciela. (more emphasis on “a bit”)

You can also drop on if the context is clear:

Jest trochę zazdrosny o mojego przyjaciela.

Things like:

On jest zazdrosny trochę o mojego przyjaciela.

are possible but sound less natural; Polish usually puts adverbs like trochę before the adjective or verb they modify.

So: keep trochę close to zazdrosny (or just before jest for emphasis).

What exactly does trochę mean here? Is it like “a bit”, “kind of”, “a little”?

Yes. trochę literally means “a bit / a little (bit)”, and here it softens the adjective:

zazdrosny – jealous
trochę zazdrosny – a little bit / somewhat jealous

Similar words you might hear:

nieco zazdrosny – somewhat jealous
odrobinę zazdrosny, troszkę zazdrosny – a tiny bit jealous (more informal / gentle)

All of them reduce the strength of the emotion, just like in English:

“jealous”
“a bit jealous”
“kind of jealous”

How would the sentence change if the subject weren’t masculine “he”, but “she” or “they”?

zazdrosny must agree in gender and number with the subject.

Masculine singular:
On jest trochę zazdrosny o mojego przyjaciela. – He is a bit jealous…
Feminine singular:
Ona jest trochę zazdrosna o mojego przyjaciela. – She is a bit jealous…
Neuter singular (e.g. dziecko – child):
Dziecko jest trochę zazdrosne o mojego przyjaciela.
Masculine personal plural (a group with at least one male person):
Oni są trochę zazdrośni o mojego przyjaciela.
Non-masculine-personal plural (all women, or things/animals):
One są trochę zazdrosne o mojego przyjaciela.

So it’s the adjective (zazdrosny/zazdrosna/zazdrosne/zazdrośni/zazdrosne) and the verb (jest/są) that change with the subject.

Why is it przyjaciela and not kolegi? Don’t both mean “friend”?

Both relate to “friend”, but the nuance is different:

przyjaciel – a close friend, someone emotionally important to you.
kolega (and koleżanka for female) – a friend in a broader, looser sense: colleague, classmate, someone you know and like but not necessarily very close.

So:

On jest trochę zazdrosny o mojego przyjaciela.
→ He is jealous of my close friend.
On jest trochę zazdrosny o mojego kolegę.
→ He is jealous of my friend/colleague/acquaintance (not automatically “best friend”).

Both are grammatically fine; it’s just a question of how close the relationship is.

What’s the difference between On jest zazdrosny o mojego przyjaciela and On zazdrości mojemu przyjacielowi?

They are related but not identical:

On jest zazdrosny o mojego przyjaciela.
- Uses the adjective zazdrosny with o + accusative.
- Focuses on his state/feeling: “he is (feels) jealous.”
On zazdrości mojemu przyjacielowi.
- Uses the verb zazdrościć with dative (komu? → mojemu przyjacielowi).
- Focuses more on the act of envying: “he envies my friend.”

In many real-life contexts they overlap, but grammatically:

zazdrosny o kogoś / o coś – adjective + o + accusative
zazdrościć komuś czegoś – verb + dative (and often a genitive for “what” he envies)

Could the sentence mean “He is a bit jealous of his friend” instead of “my friend”? How would I change it?

As written:

o mojego przyjaciela = of my friend (the speaker’s friend).

To talk about his friend, you’d normally use:

o jego przyjaciela – of his friend (someone else’s; not necessarily his own)
o swojego przyjaciela – of his own friend (referring back to the subject)

In your sentence, with subject on:

On jest trochę zazdrosny o swojego przyjaciela.
→ He is a bit jealous of his own friend.

swój/swojego is a reflexive possessive; it refers back to the subject (he/she/they/I/we). jego is just “his” in general, not necessarily the subject’s own.

Can I drop On and just say Jest trochę zazdrosny o mojego przyjaciela?

Yes. Polish often omits subject pronouns when the subject is clear from context.

So all of these are possible, depending on context:

On jest trochę zazdrosny o mojego przyjaciela. – full, explicit.
Jest trochę zazdrosny o mojego przyjaciela. – very natural if we already know who “he” is.

You usually only keep on for clarity or emphasis (e.g. contrasting: On jest zazdrosny, a ja nie. – He is jealous, but I am not).

How do you pronounce trochę and what’s going on with that final ę?

trochę is pronounced roughly like:

[TRO-he] (the ch is like the German “Bach”, Scottish “loch”)

The final ę in word-final position is usually not fully nasal in modern Polish; it sounds close to a normal e, sometimes with a very light nasal quality or a hint of a “y/n”-like off-glide, depending on the speaker.

So you can safely aim for:

TRO-he (with Polish ch), and you’ll be understandable.