It could be that you had NRE for poly itself and now are coming down from that. There might be more to come in that you are just starting out with all the people you are dating. NRE could be happening with them and that will come to an end also and feelings could emerge.
I found after I had a child and took a break from poly for a bit that I got that feeling of "shooting rainbows and kittens all over the place" for everything and then crashed. It's hard to keep up the pace sometimes and hard to see through the sunshine for possible potholes along the road. Sometimes the clouds can go over and they are evident. It balanced out with time and with some break ups with people that I thought were a good match at first but ended up not being.
Take note, check in with yourself often and with the others involved and realize that it might be that none of this will last and all of it might, you just have to breath through it and make sure that your time management is in check and you are taking care of your primary; yourself.
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