Coincidentally, one of the things my grandmother and I talked about this evening is how remarkable it is that people are so resistant to saying "I'm sorry", "I was wrong", or "I don't know", when they're such tremendously liberating things to say.
When I was taking my comps (quals? I can't remember) in grad school, and I had to do oral exams, my advisor told me that I got HUGE points from my thesis committee for being willing to say so when I didn't know the answer to a question. Of course, I'd say "I don't know, but let's see... I know X, and from that we can get Y. And considering Z, it's probably... Q?" so I was still working my way toward an answer, but apparently lots of people try to snow their committee. Which is just silly, if you think about it.
And I still remember this time when I was sitting in the front row in a lecture my first year at MIT and not following the professor at all. And eventually I got over my embarassment and asked him if he could explain it again, and when he did, there was this huge audible sigh of relief from the entire room, and I realized that nobody had been following, but everyone was too afraid to say "I don't understand" to get a better explanation.
And then one night when I was back in grad school, living in the little studio off of Baseline, the apartment below me had a loud party on a night when I was having trouble sleeping. So I stomped down there all cranky and tried to bawl them out while a drunk girl pushed me out of the doorway I was trying to shove my way through. Which didn't accomplish much except to make me feel really ashamed the next morning, so I eventually nerved myself up and went downstairs and said "Listen, I want to apologize because I was really out of line last night, and I did want to ask you to be quiet, but I went about it all wrong and I'm sorry". And the really cool thing was is that not only did I feel a lot better, the guys whose apartment it was immediately started saying "no, no, it was all our fault, we should apologize to you", and it all worked out.
And I won't get into any details, but lemme tell ya, "I'm sorry, I was wrong, you were right" is an absolutely essential thing to be able to say for healthy relationship maintenance.
Why do people have such a hard time with it, I wonder? It get easier with practice, but at this point, it's so easy that I can't really remember why they ever seemed like hard things to say...