This might sound weird, but I don't even think mental/emotional issues preclude a person from finding someone--I've definitely seen otherwise! I know of two men specifically who married such women--one clearly suffering from depression and another who he knew was bipolar. And the men are actually pretty good catches. Why am I saying this? Because I think the issue is a lot simpler than these women perfecting their flaws. There's a lid for every pot. I was at a wedding this past weekend and finally noticed a clear line of demarcation between the young women (mid-late 20s) who were perpetually dateless and single, and those who were in relationships and/or married. Basically, those who were always dateless had a tendency to pine after men who were not pursuing them. In one form or another they have generally been, as long as I've known them, focused on earning or hoping to gain the affections of someone who has explicitly or implicitly said they weren't interested in them like that.
The married and/or in a relationship ones have never done that and never would. I asked my sister about it and she was like, "Yeah, I would never do that, there's no reason to with 6 billion people in the world." Basically there are people who put a natural filter on their lives and only recognize or give importance to those men who want them. That's how you find someone--you only pay attention to those who are interested in you and make those people more important than those who aren't. In so doing, such people start making up a larger portion of your interactions and the energy you invest. If a woman is reasonably attractive and an overall decent person, there is someone who is also decent who will want her. (I said "decent" not amazingly wonderful) If she rejects him, that's her choice, but she did have the opportunity to have someone. This is also where women have to evaluate their "list" and see if they're dismissing someone who will, in the grand scheme of things, make her happy. I also saw that the married/relationship ones were a lot more practically minded about relationships, whereas others tended to be more wrapped up in their "ideal type" and whatnot. Something else to consider.
And almost all these women I observed were white. I see a LOT of singleness among young white women, so I think black women tend to overplay this dearth of eligible black men in giving the reason they are single. I'm not trying to oversimplify with my theory--sometimes circumstances are just out of your control. But really, I saw a very clear and distinct line regarding these traits and I think it's significant.
Essentially, I don't buy that there's no one who is decent who is or would be interested in these women. They have to find another answer.