DEAR MISS MANNERS: A cousin has blocked me on social media. It turns out that I have grievously offended her over the last 20 to 25 years.
This is the first I have heard of such complaints, and our pre-COVID family get-togethers were always cordial. I honestly don't recall doing the things that she said I did, although I admit that my memory is far from perfect.
I also am wondering why we are discussing things that may or may not have happened, going back to the previous century. I said that I was sorry for whatever I did. (I realize that this sounds dangerously like those "apologies" that say, "I'm sorry that you were offended" or "I'm sorry that you are so sensitive.")
I really would like to be on good terms with this branch of the family, but I don't have a time machine, so I'm not really sure what I should be sorry for having done. Nonetheless, I am sorry for hurting her feelings.
Is there anything else I should do, or is the ball in her court? I truly wish that she had pointed out any offenses when they occurred.
GENTLE READER: Saving up complaints is neither kind nor, as you note, effective: No one fixes what they do not know is broken.
But just as you cannot change your past behavior, neither can she. If you wish to continue the relationship, Miss Manners suggests you not only apologize sincerely (as you have), but also make clear that you understand what you are being asked to change in the future. Then, it would be wise to show patience while you demonstrate that you are making good on that promise.