Mine didn't want to go to Alanon because he's very private, but every now and then (now that I'm recovered and see things more clearly), I'll mention it to him.
However if the roles were reversed, I admit I would probably be angry. Out of fear. Completely bat-sh*t frightened of what he was saying about me to perfect strangers and about what they were telling him to do. I'd be a basket case that I was being utterly misunderstood and misperceived. I would worry that Alanon meetings were just you all bad mouthing us for an hour, and that you all don't understand alcoholism, etc, etc.
Maybe he needs to hear that your going to Alanon is similar to his going to AA. That it's for you to work on you, and you're not going there to bad mouth him. Perhaps that'll help him to relax a bit.
Know that anger is a secondary emotion and there's usually fear going on underneath it.