@clacke I gave this sort of thing a fair amount of thought back in my early 30s. This essay was good, as I recall: https://www.theatlantic.com/magazine/archive/2008/03/marry-him/306651/
Dr. Johnson also had some wisdom on the idea of "The One":
Boswell: "Pray, Sir, do you not suppose that there are fifty women in the world, with any one of whom a man may be as happy, as with any one woman in particular?" Johnson: "Ay, Sir, fifty thousand."