Forget birthdays or an anniversary? Let's see ... we celebrated my birthday once 3 weeks early one year because he got his dates confused. Act surprised that he remembered? No problem!
So...for awhile I got a calendar to hang on the wall and I wrote the dates on it -- along with his parents bdays, kids bdays, etc., so it didn't seem too obvious. Now a days I just mention to him a few days beforehand the plans that I've made for our anniversary and my bday. 
Alright... I don't remember nothing, and never have. It's only lately that I have become more aware of the importance of these dates to others. None of it matters a whit to me, except 4th of July, which I have often missed - working right through. But by and large, having no weekends and no important days of my own, it makes it hard to fathom in others.
The only one to fix that in me was again, a sweet Georgia peach who, as Southern culture demands, was a bit of a socialite, caring also for elder relatives,and never missed an important day in her life - And whether I cared or not, it would be unseemly to attend alone, and often required hanging onto an arm.
She figured out that I pay attention to my business calendar, never missing, whereupon she conned me into sharing that PIM to her account... and thereafter all those social functions began flooding into my days. Even, with legit authority I suppose, acting like my secretary, moving my crapnaround to shoehorn in an event.
Yeah... she drove me crazy... and she always got her way. Always.
I should have married that one...