The sentence "Scusa se non mi sono fatta più sentire" means, as I understand it: "Sorry if I didn't get in touch with you anymore". Or is there a better translation? Anyway, what seems strange to me is the "if". It's somehow the same as "I am sorry in case I didn't get in touch with you anymore". But I know if I got in touch with the person or not, it's not that I need to say "if thats the case I am sorry". So basically "Sorry I didn't get in touch with you" or in Italian "Scusa non mi sono fatta più sentire". I asked an Italian native and she told me this sounds wrong/like a foreigner. I then asked if "Scusa che non mi sono fatta più sentire" is better and she meant it also doesn't sound quite right, but she couldn't explain me the details. So question to you: Do I need the "se" in the sentence? Why? Is there maybe another meaning of "se" that actually fits better? I am native German by the way and maybe it just seems strange to me because I wouldn't say it that way in my language.
4If your Italian is sufficient, you may see that among the different uses of se registered by Treccani dictionary, 1.c register a causal or temporal one, almost as if it meant since. (And by the way, in Germanic languages too the two meanings blend somewhat, if German wenn, cognate to English “when”, means both “when” and “if”.)– DaGApr 2, 2016 at 19:51
According to Maria Cristina Peccianti in her Grammatica italiana per stranieri, the conjunction "se" has also a causal function, that is, it introduces the motive, the reason or the cause of the principal clause. In your sentence, "se" introduces the reason for asking for excuses.– Charo ♦Apr 3, 2016 at 10:45
This causal function of the conjunction "se" is also explained in the Treccani dictionary entry mentioned by @DaG.– Charo ♦Apr 3, 2016 at 12:57
You can say (ti chiedo) scusa per non essermi fatta più sentire, which maybe makes the causal meaning clearer. Se is the usual conjunction, though: the per makes it sound more formal and detached.– LSerniApr 10, 2016 at 15:43
what seems strange to me is the "if". It's somehow the same as "I am sorry in case I didn't get in touch with you anymore".
I agree with you, that seems a bit strange to me as well (and I am Italian). However, se also as a causal function as outlined in the comments to your question. Let me add this could also be used in an "angry" way to reply to one person if you are fed up with their request. Example:
Scusa se quel giorno lavoro!
This literally means «sorry that I work on that day» but it can be read as «Oh come on, you know that I have to work and I can't go out with you, then why are you mad at me and acting like you are offended»... well, you get the idea. :)
Now, regarding whether you must use se or not:
I then asked if "Scusa che non mi sono fatta più sentire" is better and she meant it also doesn't sound quite right
That is indeed incorrect, however children or people who do not have a very good education level make this error quite often. You would still be understood.
Do I need the "se" in the sentence?
You can use the following form:
Scusa per non essermi fatta più sentire.
As a side note, you can also invert the order of fatta and più.
1I'd just add this: to me if you say "scusa se non mi sono fatto più sentire" you sound nicer than you would if you said "scusa, non mi sono fatto più sentire" or "Scusa per non essermi fatto più sentire". Actually what will always come next is: "scusa se non mi sono fatto sentire, MA...." and some excuses / real reasons after that ;)– AltGeiJun 7, 2016 at 13:29