Found: Boy from underground world

Boy around teen or pre teen
lives in large community of ungrounders
lives under a big city, possibly new york
living on land is weird to these undergrounders
most undergrounders has never been above grounds
undergrounders are probably not what they were called btw
undergrounders are mostly dirty and poor
one day boy goes above ground
undergrounders have a special name for "above-grounders" (i forgot what it was)
"abovegrounders" don't really know about undergrounders
above-grounders are like modern day humans, they live in possibly new york maybe chicago
going above grounds is forbidden torwards undergrounders
main character boy tries going above grounds with his friends
boy eventually gets to an above ground by himself
main character girl(same age as mc boy)
lives above ground with her older brother and mom
older brother is annoying and mean
lives in apartment (possibly in new york)
one day girl's older brother has a highschool party when moms not home
mc girl is chilling but then finds mc boy in her room
mc boy snuck into the above world and snuck into apartment through vent
boy is fascinated by the above ground
mc girl is freaked out and thinks he's homeless or something idk lmao
they become close friends and shows each other their worlds
i think they fall in love or something
plz help

Downsiders by Neal Shusterman?

omg yes thats it, tysm!!

>2 beyondthefourthwall: yesss thank youuu

No problem!