OP I've read your posts and felt I had to comment. From what you've posted I truly think your dh had ADHD. Much of what you've written rings true for me and my dh.
DH was always ' a dreamer', a 'bit scatty', a 'bit forgetful' and ALWAYS late for everything and always stressed trying to get out of the house. Even if he was ready to go on time, he would inevitably discover his keys / wallet / phone etc were then missing.
We argued about it and laughed about it depending. He's self employed & very successful at what he does but he really struggled with the business side of being self employed. What I mean is let's say his job was making rocking chairs (it's not!) he's REALLY good at making them and they're in high demand and he has lots of orders but he struggled with delivering on time and keeping on top of the emails etc.
To the outside world he appeared super successful, winning awards for the products etc but behind the scenes the wheels regularly fell off.
As he got older I noticed a sharp decline in his situation. It was getting worse and worse and long story short but he really, really messed up a couple of huge opportunities including a contract for 100K. It was a very low point and he cried very sad tears and said he thought there was something wrong with him. It was the first time he'd admitted it out loud.
He went for assessment and was diagnosed with ADHD at the age of 49. Honestly I was not surprised but what I was not expecting was how the diagnoses changed thing for the better.
I was far less impatient & worked up about him being disorganised, I realised that he was struggling. He worked with the psychiatrist to work out coping mechanisms and strategies and really worked at implementing them. It's not prefect and when he's tired he slips back again.
I realised that I could help him with the planning side of his work and I do this now and it's helping enormously.
Our relationship is 100% back on track. He's handsome, funny, incredibly loving and kind and a really engaged dad to our teens and I can see all that again now that I am not spending my time allowing myself to get wound up over his faffing at times.
I urge you to speak to him. See if you can get him to open up about what's really going on with him. He's potentially doing his best to mask things, unsuccessfully, but that in itself is exhausting for you both.
I wish you all the best and hope that you can both work it out.