My Non-ADHD Partner Always Feels Invalidated... Help Me Validate Him!

My partner (NT) very often says that I (Dx) leave him feeling invalidated when he brings up issues with me. He has stated that my initial reaction of getting defensive makes him feel like he's unheard and unseen.

I have been actively working on becoming less defensive when he brings something up to me, but clearly it has not been enough. I backslide sometimes into becoming defensive before I validate his feelings, and it's really taking a toll on him.

Would anyone be able to give me some tools or insight on how I can allow him the space to feel his emotions and help prevent me from disregarding him?