The one thing I really miss, being single and living alone, is having that one person to talk to about anything. It's not the same telling bits and pieces to various friends--I'm largely invisible. When someone else is witness to your daily existence it lends meaning. The interesting things I see, or funny thoughts I have, are left to rattle around in my brain, unshared. Not that life is awful, just lonely. And I've had more than enough loneliness for one lifetime.
Btw, there's such a huge cultural bias against admitting to loneliness. We're supposed to be happy with our own company, self sufficient, able to cope. What is that about, I wonder? Part of the do-it-all-yourself, by the bootstraps American image? Examining cultural precepts is fascinating. But then I'm weird that way ;)