The "forgetful" mode

Asking a question here............. I've read in the ADHD books (including Melissa's) about the ADHD forgetfulness. This forgetfulness is extreme and rampant. I see this in action when it comes to my ADHD husband's remembering important things that concern me or the family, etc., but mainly I see it in how he "forgets" what he/himself says and/or does. He says very hurtful things, behaves in hurtful ways BUT when I ask him about it he says "I don't remember that". But he will remember EVERYTHING someone says or does that hurts HIM......even "perceived"  slights. He sees slights were there are none, but doesn't recognize or WANT to see when HE hurts people.  Now to the question.........WHY don't the ADHD folks remember things they do on a regular basis? or is it a defense mechanism that use to get out of sticky situations. OR a true brain problem of remembering?....or both? when they say....."I don't remember that". Do they REALLY not remember? There are hundreds of stories here about ADHD spouses (many husbands) who won't accept their spouses "verbal side" of an issue. They deny, blame, accuse the spouse of making things up about them, etc., when we AREN'T, but this is what they do, and how they feel.  I know JJaimeson has quite a handle on his ADHD and works it religiously, which I applaud with thunderous applause....(Hi, JJ) I'm just asking to see what any of the rest of you think.