The intense excitement and infatuation at the start of a new relationship, which can temporarily overshadow existing ones.
NRE is the giddy, can't-stop-texting, everything-they-say-is-fascinating phase of a fresh connection. Racing heart, no appetite, checking your phone every ninety seconds. Monogamous folks call it the honeymoon phase; psychologists call it limerence. Non-monogamous people gave it its own name because they needed to talk about it as a thing that happens while other, older relationships keep going — and can get bruised in the process.
That's the misconception worth naming: NRE feels like evidence. The intensity reads as "this one is different, this one is real." It isn't a verdict on compatibility — it's a neurochemical weather system that fades in most connections within months to roughly two years, whoever you are and however good the match. Reading the high as destiny is how people torch a solid long-term relationship for a spark that would have cooled on its own.
Where it actually shows up: cancelling on old friends, mentally checking out of an existing partner, agreeing to things you'd normally think twice about. In polyamory the community developed etiquette around it precisely because one person's NRE is another partner's neglect — hence the counter-concept of ERE (established relationship energy), the quieter, deeper thing NRE tends to make you forget you have. The move isn't to suppress the high. It's to enjoy it while remembering it's a narrator you shouldn't fully trust yet.