seminary, where we were told that lots of singles are still waiting around through their own fault, they say no to a boy for invalid reasons
That is quite horrifying. How is anybody supposed to date if they think every decision is either totally good or bad?
The better view is that there are many people one can marry and it will work reasonably well, if you try to make it work. So if you say no to someone, there will be another. If you marry someone who you are pretty happy with, it will work even if there is a “better” one out there.