YOU SAID:
I could leave the party without ever letting you know
INTO JAPANESE
私はあなたに知らせることなくパーティーを離れることができました
BACK INTO ENGLISH
I was able to leave the party without informing you
INTO JAPANESE
あなたに知らせることなくパーティーを去ることができました
BACK INTO ENGLISH
I was able to leave the party without informing you
You've done this before, haven't you.