If every friendship had to explain why it began, how many would survive the explanation unchanged?

Many friendships began for reasons that have nothing to do with why they continue: proximity, a shared class, an accident of seating. Explaining the origin honestly would sound unflattering, and it would say nothing about the twenty years that followed. Beginnings are usually arbitrary and endings usually are not.

This should reduce your anxiety about how new relationships start. The origin does not have to be meaningful for the thing to become meaningful. And it is a reason to say yes to accidental proximity: classes, groups, regular places. Most of the people who end up mattering arrived by a route neither of you would have chosen.