I think it’s because it is then that you are strong and sure in yourself. You don’t need the partner/romantic relationship, you’re not dependent on it, which automatically puts you in a better position. People see those who don’t need them as more desirable. I’ve seen it many times but it took me a long time to figure out how to get there myself. By saying I’d be okay with being by myself, it doesn’t mean that I wouldn’t have liked a partner - it means that I was okay without one, with just myself. It’s attractive to others because they know you can take care of yourself and that you will be okay with or without them, not dependent on them.

I feel the “when you stop looking” refers to all of that. The self-possession, self-containment, “closed system”, etc. It doesn’t mean to stop putting forth all effort or seeking opportunities, just that it’s not the end-all, be-all. That you’re not so invested in it or the outcome of it, you know?