New to Forum : Therapy Issue - please help

I recently began therapy for myself.   I am not in a particularly bad place in my life but I want some help with some issues that are holding me back.   One issue are some of the disconnects between my husband and I which I talked about during my first session.  My husband has many of the characteristics of ADHD including irritability and impatience, and some communication issues.  My therapist suggested he had ADHD and I casually agreed because on the surface it appears that way.

During the second session we had talked about some re-occuring dreams I have had.   The message of which the therapist related to me wanting to leave my husband.   I don't want to leave my husband in waking life.  We have only been married two years.   We have a tender relationship and I really love him, though I agree with the therapist there were signs in the dream that part of me wanted to run away from the marriage including a not so subtle dream in which I did run away. 

The note we ended on during the second session was the therapist telling me that my husband had ADHD, that he was wired differently, and was not really ever going to substantially change, and I needed to needed to decide if I could accept that.

I feel like she shouldn't have tried to diagnose him without ever having met him.   And I thought it was awful of her to say he would never substantially change.   It felt so harsh and depressing.

I have faith that if that there are core things he can work on with the help of his own therapy and possible techniques like mindfulness meditation which he is committed to.

Do you think the therapist was irresponsible to say he had ADHD and wouldn't change because of his different wiring?