Hi! Author here. I'll admit I struggled to find a more precise word than "context". What I mean is that a friendship is not the 1:1 interaction you have with your friend, but that friend's omni-directional interaction with every other friend. Their location within a network is one way of putting it. In other words, their entanglements in your web of mutual commitments, shared history, and collective responsibility.

Maybe think of it like a shared challenge. You might be going through parenting together, or starting a business or some path through life that you have in common.