Not everybody does and most that do remain single didn’t really have much say in the matter.
However, the best thing a perpetually single person cvan do for themselves is focus on enjoying life and developing their talents.
They’ll make themselves a more interesting person if somebody does come along. If the single person remains single, they’ll enjoy life more regardless.
You’re quite right; a lot of nice people don’t want to lower their standards and so they remain single. Often, the standards are not unreasonable ones when you look at the mess people are these days.
I am not trying to proselytize but go to church. Let God guide you to the only true happiness.