i was thinking the hs sweetheart was someone that she dated pretty much throughout hs, maybe even a year into college, before they realized they just worked better as friends and were kind of just going through the motions by the end of it? so it would've been an amicable split, and they're probably still friendly. the close friend guy would just be someone for a group that met as freshmen and have been close ever since! go on a big trip together once a year, have group dinners and outings and things (that gretchen is usually late to and it's a 50-50 chance ellie even shows up because she plans most of their outings but loses track of the day p frequently, lmao), just a cute little friend group, basically.