NRE is no excuse to throw you to the side, though. Anyone experiencing NRE has a responsibility to any partners they already have to make an effort not to become completely engulfed in all the new, fun feelings. NRE is not license to ignore or neglect partners, family, or even friends.
Asking her to manage her NRE, to be responsible and find a balance between the two of you, is not "stifling" anything. It's asking her to be a mature grown-up who deals with the realities of being poly.
Pan Female, Hinge in a V between my mono (straight) husband, Monochrome and my poly (pan) partner, ThatGuyInBlack