I almost chimed in with my 2 cents earlier but I wasn't feeling up to it.
Why don't you just leave the husband alone? Stop trying to explain, encourage, share with him stuff. If a metamour was nonstop trying to get me to see their viewpoint or reassure me when I just wanted them to leave me alone and give me space to think, I'd be beyond pissed off. He needs time and he's not going to feel like he's getting it if you're spending HOURS talking to him. Youre not dating him, you're dating her. Men don't like to spend hours processing their feelings in general from what I understand, so just back off and keep your conversation with him in the neutral friend zone, back to topics you discussed BEFORE you got involved with his wife.
Happiness will never come to those who fail to appreciate what they already have.