b) I think almost everyone is pretty much doomed to fail in some big ways relationship-wise. Maybe 5% of humanity manages to get past their issues and make a relationship work long-term; everyone else will fuck it up, and a lot of times it happens before they understand what's happening and only become aware of how it could've been fixed once it's too late.

That pesky lack of omniscience.

Because yes, ultimately communication is a poor substitute, because there is deception and self-deception too.