unrequited besties
When one person thinks you are best friends, but you in turn consider another to be your best friend. This chain can involve many until two agree upon their mutual bestiship.
Patrick wanted to be besties with Erik, but Erik considered John to be his bestie. John thought Kate was his bestie, but Kate is actually besties with Karen. Karen & Kate often laugh at so many unrequited besties within their circle of friends and are happy they have each other as true besties.