For well over a decade, I insisted that Setanta's birthday was 2 days before it really is. Insisted. You'd think I'd eventually let him have his birthday on his birthday
Thank goodness for facebook. Now I let FB tell me when it's Set's birthday.
Luckily neither of us lets this kind of thing have any kind of meaningful effect on the relationship.
Movies, colours, birthdays ... minor blips in a relationship. Not hills to die on in a relationship.