If you have known one or more of these characters, we have only one piece of advice to give you: Take control of your FEAR. Identify what it is that prevents you from slamming the door on these pretenders, and start to confront it. Don't fall for the same tricks or settle for mediocre treats. Otherwise, you'll end up trick or treating a lot more than just your love life.
If Clara looks around her workplace and friends she notices a surplus of single women in her age range. This of course puts her at a disadvantage: if she has to compete with women for fewer available men, she will have to trade below par, or in plain terms, lower her expectations below what she could get in a more gender balanced environment.