Neglect, Alienation
Noun and する verb
そがい
学校ではずっと疎外感を感じていました。
I had constantly felt alienated in school.
Neglect someone so much that you remove yourself from their inner circle and live outside of their life and it's called estrangement. You might never see them again. But that's okay with you, your relationship is too weird to fix now.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.