Maybe I just THINK I'm very invisible, but it's selective noticing. (I notice strongly the times I'm invisible and then don't notice the times I feel like part of a group.) Hard to say.

I admit that I too don't remember a lot of important things, often things very important to others, so that's something I can think about when musing on friendship. If I'm not remembering what's going on in so-and-so's life, then are we close enough that I should expect him to remember mine? Having reasonable expectations is probably key.