Having re-read both this and the thread which S posted I can see that NRE affects people in different ways... We really do all date differently!!
S talked a lot about the NRE feelings she was having towards me and I guess I didn't really understand what she was referring to. I felt this enormous sense of wow, this feeling of "this is amazing!!", but I didn't do so at the expense of time with my existing partner B. EDIT - I should point out B and I split up about 3 weeks ago, though this was more because of distance than anything else. We've stayed great friends and have agreed to tag on the "with benefits" whenever we're in the same city.
I felt I settled into a relationship with S very quickly and was totally smitten
That feeling hasn't died down, nor will it. I consider myself exceptionally lucky to have fallen on my feet so cleanly in the poly community with me being so new, and even more lucky to have found someone who makes me so happy.
I found it hard to relate to the NRE she was talking about as it just felt natural and normal, it didn't feel like an overpowering sudden emotion which blew me away and then fizzled out to nothingness - it was just right. By contrast S talks about how she hardly recognised there was a room around us let alone other people in it. I think she's scared that if I date others I will be affected by NRE in the same way she was, rather than affected again by it in the same way I was.
Whether I identify as mono or poly, and whether that identification is ever under review I do want to continue to uncover and work on any insecurities either of us might have and work through them. I feel in my heart I do have the capacity to love more than one person and maintain those relationships healthily, but I want to reassure anyone I date that I will never put other partners needs first at the expense of theirs. So in this instance I wouldn't ever let my feelings for J (or any other girl I might meet) affect the love I have with S or the time I have with her.