[lisper]

> we can pick up where we left off after years of minimal contact

Sure, but you have to actually do that from time to time.

I've lost count of the number of people I thought I was really close with who moved away insisting that they would keep in touch, and then I never hear from them again, ever after reaching out.

(Having kids is another reliable "friendship"-killer.)

[SoftTalker]

Yes, I've never had a friendship survive a relocation. Not to say that I dislike or resent any of these people at all; we simply never talk anymore.

Kids could possibly do the same especially if your friends are not also having kids at the same time. Kids can also easily contribute to the making of new acquaintances (parents of other kids) as well. These might turn into friendships, or might fade out quickly once the kids' interests diverge (or they grow up and leave the nest).