Repeated interaction is a necessary first step to friendship, you cannot befriend someone you don’t see. My gym buddies are now my friends, and we see each othe

Repeated interaction is a necessary first step to friendship, you cannot befriend someone you don’t see. My gym buddies are now my friends, and we see each other regularly outside of the gym context. Also, most of my friends don’t know when my birthday is, so that’s a bad metric imho. Birthdays are not universally important across the population.