We aren't destined to be entwined with one another. True loves, soul mates, BFF's, whatever.
There is no Almighty Being holding us together like a child yelling 'Love each other!" like we're dolls in His or Her playroom. The universe isn't, hasn't, and won't conspire to make things work that way. These are knots we tie ourselves. No one else is binding us to the problems that we have. We can bind ourselves, and others, to our own problems very well, thank you very much.
Yes, it's a great deal more complicated than that. There's familial motivations, financial issues, psychological problems, etc. But the real reason is dependency, plain and simple. That's what entwines us. That's what binds us together. That's what makes friendships last longer than they should, and the realization kills friendships long before they should die.
I'm not talking about being dependent financially. That is a problem that a willingness to work hard and face the consequences can deal with. It will suck and you might not win in your lifetime. Assuming you have a win-condition with your finances, in which case you have planned much further ahead than I have. You can be financially independent of parental and governmental support. It's hard, but their help is not something you need. Unless you are taking care of three kids and are yourself a paraplegic, in which case you are more than free to ask for help. Because, seriously, that sucks.
I'm not talking about being dependent socially. Sure, we usually end up sharing a social circle with our romantic partners and our friends. My friend will usually turn into another friend's friend, and all that. But all that, friends and lovers, can be replaced and rebuilt, over time. Another life, another set of friends.
Psychological problems concerning dependency is a subject I am neither experienced with nor qualified to talk about, so I'll just skip over that.
I guess what I'm saying is that there is nothing forcing us to be entwined with the people around us. We don't need them to survive. Anything that can be replaced by something else is, but that very fact, unnecessary.
We need up being entwined with the people around us because we like being depended on, and like depending on others. The first makes us feel important, even if our role isn't a necessary one. Someone's coming to us with their problems, whether they are medical or financial or emotional in nature. That means we're special, right?
We like depending on others because it makes us feel relieved. The day-to-day needs of work, providing food, as well as the natural desire for social contact, entertainment, self improvement and so on can often seem overwhelming to even the strongest of us. And to have other people in our lives that we can expect to help us with these problems makes the burden, at least feel, lighter.
But we are not destined or forced into this. It's a personal choice.