ADHD partner has insight, but lacks action

My husband was diagnosed earlier this year and it's been a hard journey. The diagnosis brought up a lot for him and he went into a pretty unhealthy place for a while. I have stood by him, while giving him space to work through things. He has previously been a very good partner for 5 years before being diagnosed. This is all complicated by his small business ownership and that being a point of contention because of the usual financial and hyperfixation issues. But in the last 2 months we have both made progress towards healthier interactions. 

He recently went travelling for 3 weeks for work and while he was away, had some realisations or insights into things about himself and us that were quite profound. I felt heard and validated and was really looking forward to him getting home. On his return however, I feel we have taken a number of steps backwards as the stress of business ownership and life in general kicks in. He seems to go into these wound up episodes where I can't reason with him. I know I don't always approach situations with what he needs and I am trying to be more empathetic.

I do have hope because he is willing to put work in to himself for the sake of our relationship and for himself too. And his insights while he was away proved that he is not in denial about some of the challenging traits of his ADHD. I'm not expecting a crystal ball, but I guess I'm seeking other people's experiences with this. Does insight ever slowly translate into change? Can symptoms be exacerbated after a diagnosis and eventually level out?