OP, I don't fit within your parameter as I'm only 42. I have never, however, been in a relationship (with the exception of a nine-month fuckbuddy stint which ended when I moved. It was nothing but sex, though).
I am a textbook introvert. I am a former fat kid, so I hate my body, no matter how good a shape it's in. I have HIV. I have bipolar type II, social anxiety disorder, and major depressive disorder, all which I take medication for. Due to my medications, I have erectile dysfunction and am therefore, after 25 years as a versatile top, a bottom whether or not I want to be. I'm currently underemployed with no major assets. I'm extremely insecure about my looks and my place in life. I would not even date myself. Seriously. I don't know why anyone else would either.
Many people, from acquaintances to my (gay) dentist ask why I'm not in a relationship. They tell me I'm attractive, that I'm intelligent, that I'm funny. I suppose that, objectively speaking, there is a grain of truth to these observations. But,of course, I feel like whale shit at the bottom of the ocean. The guys who have recently come on to me, I do not find attractive. Back when I felt very confident in my body and looks, I had a lot of sex with very attractive men -- but booze or drugs was always involved. Now that I'm sober, I realize that these guys wouldn't touch me without the aid of mind-altering substances. Unfortunately, I think that period of my life skewed my perceptions of the type of man I could attract. I won't consider dating anyone less attractive, less motivated, less respected by his peers than I am. I want to be the ugly one in the relationship -- I don't want to date "down"; "across" would be a stretch unless he were hilariously funny or goofy (total weaknesses for me). I tend to be emotionally dead when dealing with other gay men, other than the fact that they make me extremely anxious. Extremely. I always come up with an excuse to leave a gathering after a max of two hours, and that's even when I'm in the company of a friend.
After being severely burned four times in my life, I have resolved to never again make the first move. I can't deal with the rejection. I just can't. It sends me into a minimum of a six-month depressive episode. Minimum. Each of these four men chose another man over me. Seriously. It's as if I were in direct competition with the other guy and I struck out each and every time. I become the friend. The friend who still has a crush. After a while, I just extract myself from the whole equation.
I don't understand the people who say "you just have to love yourself first!" I've never loved myself. Ever. And after 42 years, I don't really see it happening.
I do have a great circle of friends I love. I've decided that now my dream is to buy a big farmhouse and have my friends come visit whenever they want, for as long as they want. This is my version of heaven, my adopted view of happiness. I hold out for The One in vain; I know he'll never come. Sometimes I cry, sometimes I sigh, sometimes I just stare off into space. But I realize this it. Half my own making, half not. C'est la vie. At least I'm not an orphan in Darfur.