I am one of them. I have no aspirations for a long-term, let alone lifetime, commitment to another person. I could have sex regularly if I wanted (although COVID has made me celibate for various reasons), but since my 20s I knew deep down that a life partner was not in the cards for me. I'm in my late 30s now and very much set in my ways.
I have tried to dissect and analyze my true motivations, and I'm always torn between two explanations for my single-hood: I'm either 1) genuinely solitary and happier alone or 2) somehow unable or unwilling to make the necessary interpersonal sacrifices needed to sustain a long-term romantic attachment. I would be remiss if I didn't add I have a lot of "issues": I can be needy, I have bipolar disorder, and the brief relationships I did have in my 20s ended badly.
Now I wonder if I'm lying to myself, and if, at heart, I crave a partner. I met a new colleague recently who is in her mid-50s. Never married, never partnered, no kids, and maybe a lesbian, but it's never come up. She confessed to me that she is lonely all the time, especially since her parents died, but added she prefers to be alone. She is attractive, generous, and easy going: I have to imagine she is single by choice. When I look at her I fear what the rest of my life holds. I remember being in my 20s and hanging out at the gay bars and meeting unpartnered eldergays who seemed lonely. In a few years, that will be me.
I guess what I'm asking is ... do you think "single by choice" is largely a defense mechanism? If given the choice, do healthy people choose companionship?