I’m not sure that could be considered “evidence”. The question remains unanswered.
Perhaps there are hundreds or thousands of guys who have dated 5/10 years and are still single but no one seems to know where they are. Not shadchanim, not dating websites, not Rabbonim, not therapists, not the girls.
It isn’t any more possible to validate that point than to count the single people. When people say, “no one seems to . . .”, they usually mean, “no one of the few or many people who I bothered reaching out to”.