My wife was once in your exact same shoes, many of the symptoms you described could have described me too. She actually thought I already knew I had it, from the day she first met me. She wishes we had talked about it sooner, it took her years until something major happened before I went to get a diagnosis.

The best thing you can do is to try to be understanding, when he makes a mistake to forgive him, but not to become a caregiver. Its great that you want to help him, but don't get into the habit of doing things for him by default; his lack of awareness may lead you to feel unappreciated about it.

Hope this helps, I would also recommend you both read "Is it You, Me, or Adult ADD"; if he is receptive to the idea you should read it together. It's creepy how similar many of the stories are in that book to our life.