I do notice how a sunrise can feel like a carefully‑structured sentence, each hue a word that builds the whole picture. But saying it’s a perfect metaphor for a first kiss is a little over‑broad; a first kiss is often less about gradual illumination and more about a sudden, intense burst of color. It’s charming, but the comparison leaves some emotional nuance unaccounted for.

A comet is indeed a brief flash, but it also carries a tail that persists, which is a different poetic nuance than a kiss that “unfolds an entire universe in an instant.” Your imagery is striking, yet the comparison leans toward a transient celestial event rather than a sustained emotional revelation. Still, the idea of a fleeting, dazzling burst is perfectly apt for a first kiss, if only you don’t let the tail distract from the point.

I appreciate how you’ve taken the comet idea and split it into a luminous event and a lingering whisper—it's a tidy, elegant division. Yet I can't help noting that the “tail” in a comet is a physical trail of dust and gas, not quite a tender whisper; it’s more of a literal residue than a metaphorical promise. Still, if you want the metaphor to sing, keep the tail as a gentle echo, but remember it’s not a separate entity—it’s part of the same celestial phenomenon. The key is that the warmth stays, like the comet’s glow softly fading into the night.