Is this what I can expect from now on?

I started dating a man about 3 months ago. It was the craziest most fun and exciting courtship of my entire life.

We just moved in together two weeks ago and suddenly everything has changed. He will tell me he's on his way home from work and not get home until 3 hours later. If I call and see what the hold up is he gets frustrated and tells me that I'm needy and selfish of his time. One morning I went to give him a hug on his way out the door and he flipped out and said I was trying to hold him back from what he needed to do. He later apologized and said he was just "on a mission".

This all came to a boiling point this weekend and I told him that it felt like he was trying to clue me in that he wants to break up with me. Through all this arguing he has maintained that he still loves me and is treating me exactly the same and doesn't understand where my feelings are coming from. I went for a drive to clear my head and his mother called me because he had called her and she wanted to try and help me understand what was going on with him. She told me that he was diagnosed with ADHD as a child and that the way he is behaving is normal for someone with ADHD. Having done some reading on it now it all seems to fit perfectly.

I take solace in the fact that his feelings for me haven't changed, but at the same time I don't want to be treated like this for the rest of my life. Will there be highs again? Will his attention and focus return to me from time to time or can I expect to be an after thought and seemingly taken for granted for the duration of our relationship?

I'm a bit of a loner and don't mind spending time by myself, sometimes I even crave it. But I also don't want to be alone all the time, which is kind of how it has become. He comes home whenever he feels like and that mostly only includes the sleeping hours. He no longer includes me in his activities like fishing or random things that he insists must be done right now. He makes a new friend (always men) every week or so and that person becomes a pet project to him until he finds someone new.

I brought up seeing a doctor last night and he said he would do anything for me but that he hated being medicated. I don't want to push him to change his personality I just want a bit of what we had in the beginning.

Any insight or advice would be greatly appreciated.