I read this 2-3 years ago and now have no clue how much this fits your description but I immediately thought of it when I read your post for some reason. So here we go https://www.mangago.me/read-manga/bokura_no_tsuzuki
There is a list here of mangas. https://www.mangago.me/tag/popular+x+unpopular/
https://www.mangago.me/tag/Social+Outcast/

i need a bl where one of them is an outcast as in very introverted and the silent type. A wallflower, if you will.
And he gets pursued by a more outgoing guy who is intrigued by him and wonders why the other guy barely speaks to others and prefers solitude.
In simplifies terms; introvert x extrovert but more intense not your typical nerd x jock slop
HELP MEEEE I NEED THIS