A best friend is a chosen family. The relationship doesn't come with a name on the family tree, but it lasted as long as any of them. When they're gone, the grief is recognized in a smaller circle than family grief — but it is just as real. The song says SO out loud.
What this kind of song holds
Memorial songs for best friends hold the inside jokes, the trip you took, the year you got each other through. They hold the specific frequency of a friendship — neither family nor romance, but something else, with its own grammar. The song writes from inside that grammar.
What to put in the intake
Give us how you met. Give us the inside joke. Give us the time you saved each other. Give us what they always said. The friendships that earn a memorial song are the ones with their own shorthand; the song should sound like it speaks that shorthand.