go out って「恋人になる」という意味なんですか？

"Go out" like "go out on a date".

日本では何度かデートを重ねた後に「付き合ってください」と「告白」するのが一般的です。
恋人でない人とデートに行くことはありますが、「付き合う」というのは（ポリアモリーでなければ）一対一の関係です。

If you've gone on several dates, and you're asking a girl to be your girlfriend, for instance, you might ask, "Do you want to go steady?"... though this is kind of old-fashioned, no one says it anymore. In English, if two people are "going out", they're in a relationship/恋人. In American culture at least, people generally don't ask to be lovers, it just sort of happens. That's why in romantic comedies you sometimes get the scene where the guy asks something like, "So... does this mean you're my girlfriend now?" It's confusing.

If this is not what English speakers would likely say, maybe we should simply delete the English translation.
We're collecting sentences that native speakers would actually use. If people don't usually say the same kind of thing in the target language, it's best to leave it untranslated.

Or, if this sentence sounds natural by itself, I can simply unlink it from the Japanese.

If you were confessing to someone you like that you weren't previously dating, this would be a natural thing to say.

There's no equivalent if you're already dating, so if that's the case, I guess either unlink or delete.

All right. I unlinked it.

CK, there isn't one that I know of for the situation he described.