I think we can make this really easy: There’s only a few definers to distinguish YA from NA. In YA, the protagonist is generally not (1) sexually active and (2) not self-sufficient. YA is about finding out who you are. If it’s not clearly -all- about their Coming of Age and finding themselves in the present story YA then, it’s usually a prequel to coming of age (which I guess would be MG or younger YA).
New Adult fiction is unique because the protagonist is already sexual and independent, but there’s still new ground to be explored unique to people of a certain age group. (under 25 if I have to name an age) New Adult = New Ground to cover, but on their own terms, not via a parent, a first lover, or a le bel inconnu discovery.
New Adult stories are not journeys of life-discovery or Bildungsroman.
——Your protagonist has already knows who they are——-
Is it Erotic Romance or New Adult? If they’re boinking like minks, it’s Erotic Romance FFS! Do the math. New Adult can contain sexual content, but New Adult is not solely sexual content wearing a t-shirt that says “Veneer of Plot”.
If the focus of your new novel (that’s not simply a standard romance tale and that you believe may qualify as New Adult) is quite obviously not on the “steamy bits” or the emotions, then it’s New Adult. And don’t lie to yourself! You know how many sex scenes you wrote!
New Adult that contains romance: New Adult can contain romance. In fact, New Adult can have lots of romance. What distinguishes New Adult from a romance novel is (1) the age of the protagonists, and (2) it must have significant (I’ll say it again: SIGNIFICANT) other points of story focus aside from the relationship.
Example: Angst-ridden romance (without a ton of graphic sex) between a 19 year old barista and a 21 year old supermodel (not naming genders here) where someone gets cheated on and there’s a car accident maybe and oh a jetflight to Paris = romance, romance, romance.
Angst-ridden romance (without a ton of graphic sex) between a 19 year old barista and a 21 year old supermodel (not naming genders here) where someone wakes up with amnesia and there’s a plague or a political coup maybe or someone finds a dragon in their backpack and oh a steampunk airship flight to Paris = new adult. Because we would totally be spending a lot of time on the elements of plague, coup, dragons, and airships, not JUST how the protagonist is feeling.
Does that help?