Is this ADHD or just us?

I've been reading these forums for about 2 years now, and have finally registered to post.  My DH hasn't been officially diagnosed, but the therapist we saw when I had PND agreed that he almost certainly has ADD.  In fact she laughed when he asked, and said oh yes.  I'm seeing a pattern in our interactions which I don't seem to be able to break (and which leaves me baffled) and I'm hoping someone here can help me work out if this is ADD or just our relationship.

As an example, this evening he was playing with our daughter - they are doing pirates at nursery - and he said to her 'you can't go on the pirate ship, girls aren't allowed on pirate ships'.  I said, of course they can - as basically he was telling her she couldn't play the game she wanted, and also it is very important to me that our daughter doesn't get told at home that she can't do things because she's a girl, she gets enough of that from her peers!

At that point he went off in a tirade at me, asking me if I'd phone the police if I saw someone shot in a movie, said that he'd been playing with her all evening but now this meant it all counted for nothing, and that he wasn't going to play with her - she could just watch CBeebies where nothing controversial ever happened.  I should have married a kids TV presenter if that's what I wanted.

Is this kind of reaction common?  Does one not-completely-positive reaction from me totally cancel out everything else?  This is happening more and more often and we can't seem to get beyond it.  Either I agree with everything he says and does, or he sees me as being totally critical and himself as a total failure.

Help please someone.  It's 4.30 in the morning and I'm out of ideas.  There's plenty else wrong with our relationship (and we're on a waiting list for therapy in 4-6 months) but this is doing my head in.