Of course, had you thrown a big party on the actual day and invited me, I would have wished you a happy birthday there and then... But, as you didn’t, I’m wishing you a late happy birthday instead!
It’s completely understandable that you might be feeling as though I forgot your birthday this year, but that’s simply not what happened! I just couldn’t remember the exact day!
I knew it was around this time, so I at least deserve partial credit for that, right?