Even before my 1st marriage ended, I began studying relationship things in books and came to realize that our basic problem was the neither of us KNEW HOW to make a relationship work! She was older and had been in very serious and committed relationships before so I assumed that she know what she was doing BUT not according to the things I was learning both in therapy for my messed up emotions but in those relationship books. There were only a few very simple relationship skills and techniques to learn but she would have nothing to do with all that nonsense like: 100% honest, loyalty, respect, affection, equality and some other easily enacted skills so, I finally got fed up and LEFT HER! She preferred to stick with her tried and true methods of control, intimidation, blaming, shaming and endless FIGHTING which I was learning to stop doing in place of respect, dignity and LOVE! I divorced her and married a woman who not only believed in and wanted to use these new and improved skills but we have been using them for 22 BEAUTIFUL years now. It's so easy and beautiful to be polite, friendly, in love and HONEST with a partner but I was never taught any of that by my very flawed parents so it was all new to me. So the bottom line for me is that I could have a good relationship with almost anyone provided we both know and USE some simple, basic relationship skills which very few even know about.

If they don't want to be alone, they might have to improve their relationship skills and then open up to being found by another person with the same knowledge.

Then I'd say such a person MISSED THE BOAT on fixing or acquiring some good relationship skills and techniques that might have connected them to a good partner.
IMO, it's all about skills and knowledge which very few of us are given at home by our equally faulty and lacking parents who had equally faulty parenting before them like a multi-generational disease.
Good luck fixing up your relationship skills - google it!
jim