Do you think the way we live today makes forming middle circle relationships more difficult?
For the vast majority of Homo sapiens' history, we lived in small, nomadic bands. The tribe, not the nuclear family, was the primary unit. We lived among others of various ages, to which we were tied by generations of kinship and alliance, throughout our lives. Those are the circumstances in which our biological and neural equipment evolved.
It's only been comparatively recently (about 10,000 years ago) that we developed agriculture and started living in semi-permanent communities, more recently still that were thrown into cities, crammed up against people we barely know, and more recently still that we bounced out of cities and into suburbs.
So everything about how we live now is "unnatural," at least in terms of our biology. Of course, that doesn't mean it's bad — it's generally a bad idea to draw normative conclusions from evolutionary history — but it should remind us that socially constructed living patterns have shallower roots than we might think from our parochial perspective.
Point being, each of us living in our own separate nuclear-family castles, with our own little faux-estate lawns, getting in a car to go anywhere, never seeing friends unless we make an effort to schedule it — there's nothing fated or inevitable about it.