So according to Can someone break down かのじょ and かれ for me? it seems that 彼 and 彼女 are words that only came to mean "he"/"she" due to the influence of the West. But I'd like to know a bit more about how those third person pronouns came to mean boyfriend/girlfriend. Some preliminary research indicates 徳川夢声 might be behind the reason for 彼氏 and 彼女, but if any additional light/specifics could be shed on the top that'd be great
1 Answer
Let's look at these two in turn.
彼氏【かれし】
According to Shogakukan's 国語大辞典【こくごだいじてん】 (KDJ) entry here, 彼氏 initially meant just "that person", derived as 彼【かれ】 + honorific person suffix 氏【し】. Apparently the honorific was used a bit ironically, and the term was actually intended as a slight pejorative. If the entry is anything to go by, it appears in texts starting from 1929, in one of 徳川【とくがわ】無声【むせい】's works.
A bit later in 1934 in a piece by 永井【ながい】荷風【かふう】, we see usage in the sense of "boyfriend, male lover". This appears to be a straightforward extension of the meaning "fellow, guy" in usage patterns like "she's got a guy, that's her fellow", where the "boyfriend" sense arises out of context. Compare German usage, where Mann literally just means "man", but in the context of talking about a woman's relationships, it also means "husband". (The English term man is also used the same way, albeit in a more informal speech register.)
I suspect that both terms were in common use before either publication appeared.
彼女【かのじょ】
Here's the KDJ entry link. Use in the "she" sense as a female third-person pronoun shows up in 1885.
Then the "girlfriend, female lover" sense shows up later, and is recorded in the 1931 ウルトラモダン辞典【じてん】. I don't see any usage examples from that time, but again, my hunch is that this too was an extension of the earlier "she" meaning: "he's got a girl". Compare German usage, where Frau literally means "woman", but in the context of talking about a man's relationships, it also means "wife".
Once again, these meanings were probably around for some time before they were put to print.