It sounds like you are on the right path. Research and learn. Polyamory provides a new perspective that is not what we grew up with. The standard model of relationships is based on possession. In polyamory, it is based on desire to be together.
I have been the guy in the middle and it was hectic. I didn't learn till too late that i was stressing myself out when there were other ways I could handle it. Basically, I thought that if I spent X amount of time cuddling or hanging out with one girlfriend, I needed to spend the exact same amount of time with the other. A better way is to find out what they want. I had to realize we were not in kindergarten where such rules are needed. we needed to talk about desires and wants. Not everyone wants the same thing.
The wife needs to understand NRE and realize it is not a reflection of his feeling for her. He should understand it as well and realize where he starts to act obessed.
I don't know many poly single resources. If you listen to podcasts, Polyamory Weekly tends to talk about poly singles on a regular basis.