I absolutely love the concern you have for your husband
Obviously you value sustaining what you have. Perhaps having him read the stories of people online will help "put him in the headspace" of people who have similar experiences.
I remember giving my ex wife total support in exploring a relationship with another woman. The night she spent there was the longest and hardest in our relationship for me to the point of physical illness. I got caught up in the sexual aspect and didn't really think it through. She never pushed enough to get beyond my horny thought pattern LOL!
Eventually you will have to trust in what he is saying but I would explore this topic with him extensively before acting on it. Some things cannot be taken back. If a love's energy changes they are almost helpless to recover sometimes. You are doing the right thing with the right approach though I think...he obviously loves you a great deal. People often humble me in so many ways on here.