I think for us living together, it's because of the support system. Irregardless, whether because of financial needs, spiritual needs, emotional needs or etc. Living nowadays need money, unless one can self sustain in the wilderness or in the vast open ocean. Money need to be generated and replenished. Living means we will have families, friends, colleagues, superiors, subordinates, acquaintances, and etc. People have emotions and will be different when facing different things, unless we're trained to be an unemotional person. Well, I guess this kind of unemotional person may exists in the world, who knows, as this world is kinda big, too. Spiritually, is something cannot be forced, but coexist with us for a long long time.
Not sure if it's the way we were being brought up. While growing up, I'm sure we are not alone in the family, minimumly there would be a parent, even for those orphans, there would be a house of orphans growing up together. So, one cannot say he or she grew up alone. Therefore, we are used to having others around in our life, just whether we are open up with them, that's another story. But this means, similar to others, not everyone may be close to you, but there will be people that knows you exists. Why, because you were never alone from the start.
Of course, one will always feel lonely, not because there are no people around you. It's because you, yourself, don't let people come in, into your life. Maybe, there are times indeed that you need to open up. We don't have a lot of 'seekers' in this world, that can go around to seek out every single loner in the world. But we sure do have quite a number of 'carers' in this world, who don't mind sharing their cares for those who need them.
