Depending on how long the book is and whether it's a "cozy slow burn where end goal is love confession", "steamy slow burn where end goal is closed door" or "spicy slow burn where end goal is vigorous *activities*" (very generally speaking) Assuming - book is romance focused - using first kiss as a goalpost Cute/cozy: 65-99% (ending on a kiss hallmark/disney movie style, anyone?) Steamy: 50-85% (later is just cruel ;)) Spicy: 40-75% (and at 40 there's usually already unbearable tension)