Oops, it doesn't look like 'FandomsFriendship day' is a national day..

Other days

boyfriend

Boyfriend Day
boy friend

Boy Friend Day
believe

Believe Day
ruby

Ruby Day
pick me

Pick Me Day
gum

Gum Day
fiancee

Fiancee Day
first love

First Love Day
lisp

Lisp Day
promposal

Promposal Day