This is something I am learning as a late bloomer in life, as I didnt have too many friends more so business acquaintances growing up
The hardest lessons I hace learned though is during major life transitions - sometimes you are off on your own, you have to manage that transition yourself and cannot rely on anyone in particular through it
Friendships require work but sometimes they arent on equal terms either, and when things shift away that created that strong bond to begin with, people drift apart. Thats something that is hard to cope with, that sense of loss in wanting that nostaglic connection again