掲示板 Forums - How to use "in" as in abstract sentences?

Seem like a topic for the "Anything About Japanese" section, but I'll answer anyway.

If I understand your question correctly, you're asking "How do Japanese people express abstract things like being in something". Languages don't really map 1:1, so it's not an easy question to answer. I guess for your examples, they might say:

- 恋に落ちている

- 心の中の謎

The latter is quite poetic though.

Don't worry about it! It's not always going to be about using に or 中, Japanese uses different words and patterns depending on the situation. It's not a direct swap from English.

恋に落ちている is a real phrase, you'll get a bunch of songs if you look it up.

心の中の謎 is also a real phrase, but it's more "poetic". I just thought it fit best for your example.

The pain in my heart - 私の心の痛み - here it's の (emotional pain, not physical)

Believe in yourself - 自分を信じて - here it's を + a verb

For the sake of simplicity, you could say that Japanese often uses either に or 中, but not always.

It’s more about understanding the meaning than trying to find a direct translation for "in".

I think it's just an example of language asymmetry.

My native language translates much closer when it comes to the use of "in", but even then it doesn't always work 1:1.

Most of these would work with "в" (direct translation for "in"), but "He's in love" would be "Той е влюбен" not "Tой е в любов". it's a different form of the adjective.