Sally and Mikey almost drown together on a trip to the park. This event caused their bond to strengthen at an early age.
Sam accidentally sees Sally being intimate with someone when he stops by her house to profess his love on her birthday. He does not see who she is with, but comes to the realization that his friends keep secrets and have complex relationships.
Lynn admits her infatuation for her adult piano teacher at 13, but he turns her down. This is her first sense of lust, which awakens her desire as a teenager. She is devastated by her teacher's dismissal, but learns afterward that the feelings of heartbreak are not eternal.
As an adult, Sally kills herself by jumping from a bridge. This event led to the unification of the Gunners as the gathered for her funeral.
Lynn was an advanced piano player until someone sabotaged her by planting a poisoned needle in a piano key. She wad forced to have her finger removed, ruining her musical career and sending her into a deep depression.
After all of the Gunners, except for Mikey, move away from town to start their lives, they regularly update each other of their lives over email. This makes Mikey feel defeated and isolated as he stayed in town and established no new relationships.