I should've been more clear - I was responding to your first paragraph: "...humans are inherently social creatures and require regular face to face social contact in order to thrive." I wasn't implying that close relationships are a basic necessity, but that social contact is necessary when forming an identity. Even if you're handling life's struggles independently, you're still doing so within the context of a broader society. You've formed your identity as someone who is independent by reference to others who are not.

This may get complicated, and I have to leave soon, but I'll try to elaborate further when I get a chance.