My DH's coping strategy is that he is a very patient man
No seriously... it hasn't been easy and he was probably much more frustrated earlier on in the process when I hadn't got my coping mechanisms very well honed yet either. Mostly, we talk about stuff and try to approach things from a standpoint of trying to see where the other is coming from, rather than an I'm right; You're wrong kind of thing. If we are getting too annoyed to discuss something or it's turning into an argument then one of us will point this out and we'll each take time separately to calm down and discuss it later. I think an important issue here is that men and women tend to have been socialised differently in how to react when big emotions come up so when I feel attacked or get very anxious/frustrated/feel he's not understanding or listening to me I just become distraught and cry whereas most men in this situation default towards defensive aggression, so it might be even more important for you to work out a "safe word" for arguments so that you don't get to this point. Sometimes when we talk about things I actually make notes because otherwise what happens is that I get all het up in the moment and I can't take in or remember what we actually agreed to do going forward.
I appreciate that he's always honest (sometimes to the point of bluntness) about how he's feeling (which he says is hard for him but he's got better at it) and I have also learned that if something has got to a point that he's telling me about it, it means it's REALLY bothering him, which I hadn't really appreciated before because I'm more of a verbal diarrhoea type so 90% of what comes out of my mouth is just random incidental thoughts which aren't very important, and one of my things is to moan - so I'd be happily spouting off all this stuff which he'd run around fixing and feeling like he'd done loads for me which I'd be oblivious to because I wouldn't even remember that I had complained about it because it wasn't important in the first place.
One big issue we have had is my tendency to "flamingo" when I have a problem I don't know how to handle - I stick my head in the sand and ignore it until it becomes an enormous problem and this obviously isn't great when you are married to somebody and it becomes their problem too. So after this happened once or twice and he realised it was a coping mechanism of mine rather than a one off, he explicitly said don't do that; I can't live with that, just ask me if you don't know how to fix or approach something and we'll work it out together, it doesn't matter how bad it is.
In short, be blunt, it helps - particularly about your expectations, boundaries and what you can/can't cope with. But be open to him saying "I can't promise/do that" and ask him what he can promise or do - and try to get him to make an honest assessment here too because quite often we've dealt with a lifetime of adults/teachers/parents saying "You need to do X" and we've learned to agree and promise to do it even when we don't think we can because adults tend to get irate when you say "But I can't remember to do my homework every night" or something like that.
Sorry this is quite waffly - there is a good ADHD youtube channel called How To ADHD where the author refers to people with ADHD as Brains and people who love them as Hearts. So look for her advice to Hearts and you might find some helpful tips.
(This ended up so long I'll jut start a new post for the next question reply)