Even electrons in an atom come in lone pairs. And when there's only one electron in an atom, it's not stable. So what the atom does is it shares the electron with another atom to make a stable molecule. If we upscale this, it's like saying no man is an island. That no one should be alone in this world, because if he or she is, he/she will not be stable. Which actually makes sense because it is always easier to have someone to talk to, to confide in, to discuss things with (not necessarily agree with each other all the time), to have someone talk sense into you or to have someone giving you advice although we all know we won't be doing what they're saying but we still keep asking them anyway, to have someone to do things together like shopping or drinking or crying. Maybe it is really a need to have a best friend (could be anyone: a platonic friend, your boyfriend/girlfriend, sister, mom, or even your dog or cat or pet) because with a best friend everything is just lighter.