A wise thought! –
Kocha mnie jak brata
że traktuję ją jak siostrę.
Może byłem dla niej miły – ale nie we właściwy sposób.... :-/
[intended meaning: "... but not in the right way" – however I'm unsure if właściwy, with some very negative connotations, is the right word here.]
High praise indeed from a native speaker! :-)) So I apparently absorbed some Polish during my first 18 months on Duolingo...
The short "... ale niewłaściwie." – my first try – has the negative connotations: my favourite Pl⇌D lexicon (with its declension tables of nouns & verbs) listed: abusive, incorrect, indecent, improper, unseemly for niewłaściwy – terms I really wanted to avoid here.
Meanings of właściwy include right, and seem OK, teaching me that the negations niewłaściwy and nie właściwy are definitely not equivalent.
I later wondered if "... ale nie w prawy sposób" would work better.
[Posted 30 Jan 2019; ed. 27 Jun 2019 09:08 UTC]
"niewłaściwy" does indeed mean that, "nie właściwy" just means that it isn't right, so it can easily be "not the way she wanted", no judgment.
Generally negating adjectives isn't that straightforward, gluing nie- to the adjective doesn't exactly create a simple negation.
No, "prawy" wouldn't work here. It's not commonly used in any 'metaphorical' (other than 'the opposite of left') way and if it was, it would be rather about a person, not about a way.
„Ciebie” is the stressed form of „cię”. If that's where you want to focus the listener's attention, you use „ciebie”. In addition, you can't use „cię” at the start of the sentence, but you can use „ciebie”.
We generally avoid using „cię” at the end of the sentence, but it's still okay to do if you can't find a better place. You can see it in two-word sentences, for example… „Kocham cię”. As you can see, it ends with „cię”, because the only other place for it would be at the start, and we can't do that. But if we introduce the optional „Ja”, it would likely become „Ja cię kocham”.
You can only use "jako" in specific circumstances, that is when you want to say what role a given person fulfills. For example: "Pracuję jako inżynier". Similarly, it's also used on cast list in films when you list what role each actor played (example: Adam Kowalski jako bandyta).