In my case, I used to want to be in a relationship, but with age the prospect lost all appeal, and people ceased being interesting to me in that way at all. I never get the thoughts "oh, this person is really nice, I wonder whether I should ask them out on a date" anymore. I do however value normal friends a lot more than I used to. Still I need space even from friends. My life wouldn't be as enjoyable without the solitary mountain hikes and shooting photos of animals for hours alone.