I think this works in a lot of cases but a person can be wrong about something and get unreasonably upset by having others point it out, they might even yell or badger you to the point where they are forcing you to agree with them rather than them accepting the truth.

Then later, they make the mistake again but this time you can't point it out because you're are afraid they will yell at you again or worse by going into a fit of rage at you calling you names and throwing things so you just ignore it..

"Not this again, seriously do you want a fucking repeat of last time? What the fuck is wrong with you why do you always have to be right?".

Then even later again maybe it comes up while you're in public and someone else points out they're wrong or being insensitive / ignorant about something this time and now she's upset at you for not making it clear she was wrong in the first time.

"Why didn't you just fucking tell me in the first place?".

Being unreasonable can be blaming your partner for your mistakes, how can you expect them to stand next to you and "understand why you're being unreasonable" how can you expect them to say "we have a problem in front of us that we can solve together" when you're shouting and screaming at them and throwing your phone and anything hard and heavy you can find because every ounce of your being wants to harm them for wronging you.

If you're the SO, you might think you'd just drop it, don't be right, just let it slide and let them be wrong, it doesn't matter anyway, so you do just that, and months go by, your voice isn't heard but the house is calm and quiet, you're happy, they're happy and they have complete and utter control over you, just as they always wanted.