It’s an often used style element in Japanese. You will find it not only in manga but in novels and books as well. Since there’s a standard with furigana to show a reading for a word you can have “double” meanings.
Normally you can imagine the character “saying” the furigana and the word under the furigana giving aditional meaning to the word.
It can be a bit disorienting when one is a beginner. The readings you found for the words are the actual readings of these words.
For example そこ is what he is thinking (I think thats a thinking bubble at least?) and 社会 is to make sure the reader is understanding what is meant. In english you would probably achieve a similar result by writing something in braces “There (in society) …”
It’s 訳(わけ) . A word that means something along the lines of reason Jisho.org: Japanese Dictionary but is hard to translate. The sentence ends in で without a proper ending, possibly connecting this sentence to the next one or leaving a thought half completed.