Good to hear that things shift towards your relationship right now. It's important to get things out of the picture that are right at hand instead of focusing on some 'maybe-wants' later on. Both of you need to feel save and secure with what you currently have before any of you thinks about investing time and energy in the next 'big relationship project'. This would be as ridiculous as taking on some additional work for some school activity of the kids while the main work just keeps piling up.
I know that everyone defines poly with a personal touch to it, but I never heard of someone with the urge to form an intimate relationship with everyone he/she encounters. That sounds arduous and unrealistic. I mean, I am on the other end of that scale, I have had three relationships so far in my whole life and only one of those three ended. The other two are with me right now. I don't fall in love easily, therefore, I would emphasize what you said: It isn't about sex in my case. Never will be. It's about feelings and having the persons dear to you as close as possible. This doesn't automatically disqualify his point of view, it's just a bit extreme in my book.
What would rub me the wrong way is that you said he was all in for the drama and actively wants to create some with this new interests. That sounds not good. There is enough he needs to handle as soon as he gets involved with another person, if he tries to make this artificially harder than it already is, I wouldn't tolerate it in your shoes. My transition into poly was a relative easy one, but I was exhausted nevertheless more than once.
Lastly I wanted to second the point about things that can be seen as similar in a mono relationship concerning time and investment. My husband works a lot. He is constantly gone, doing overtimes and such (the next free weekend will be in two weeks for him). This is a problem for me. Always has been. It doesn't matter that my other spouse is constantly with my during that time. I still miss him and we need some time for each other as soon as we can get some. Just because I am poly and have more than one partner doesn't mean that the other will fill my need for connection and physical touch if I miss them from the respective other. Persons aren't interchangeable. As long as you don't have the confident and secure understanding what your place in your husband's/partner's (forgot what it was in your case) heart and life is, you will encounter problems. Just like not coping well if spends too much time at work, on a new activity, with his friends, and so on and so forth.
My husband and I tended to just assume most things and never really talk about most concerning our relationship. Like this image of the old couple, knowing the other, just being content with what they have and living their lifes. That was luckily true, it worked like that for us without major hiccups along the way. But since I opened the poly-can, there have been the one or other worm we would have overlooked in the old situation. Communication has improved in our case and I got to know some new sides of his I didn't knew before hand. And I loved it. It brought us even closer together. This doesn't have to be the case, but if it happens, poly (or any other relationship altering experiences) can be regarded as really beneficial for an old relationship.
Facts: 30, female, bi, v-type relationship with Sward (husband, straight, mono) and Lin (boyfriend, straight, mono), poly-fi and co-primary.