i'm definitely flexible on all of this, but what i had in mind was that he was the guy she was dating when her father died during her junior year of high school. she pretty much shut down emotionally after her father's death and that lead to their break up. she went through a heavy partying/self destructive phase after graduating high school and i was thinking that some of their mutual friends from high school probably reached out to him to see if he could try to talk some sense into her and that ultimately led to them becoming best friends