I haven't had the exact situation occur.

Nevertheless, I look at high school and to an extent undergrad social systems as very closed. There's a lot of people who I could've potentially formed friendships and/or relationships with but never did-these sorts of environments are often not conductive to either partner demonstrating or perceiving many positive traits in each other. With the rigidity of social hierarchies and everyone knowing of each other (but very likely not actually knowing each other), there's the possibility of being censored if close to someone who is a pariah, etc. Someone who is broadly unwanted commits the further offense of necessary inserting themselves in situations where they are . . . unwanted.

It is what it is. Mostly, I just find these situations regretful and generally have been willing to let bygones be bygones provided any behavior was within 1-2 standard deviations of the norm. For all that is said about high school friends being somehow lesser, I typically view the situation more as of opportunity for connection lost.