"What are you waiting for, kiss her, kiss her" is from Fall Out Boy's A Little Less Sixteen Candles, A Little More Touch Me!
It doesn't really outright say in here, but I had in mind that this takes place the summer after their high school graduation.
Natsu grinned to himself as he watched Lucy, the two laying in the grass staring up at the stars while Lucy chattered about the constellations and the stories behind them.
Lucy sighed happily and turned to look at Natsu, blushing as she noticed his staring. "It's so beautiful right now," she commented, looking back up at the stars.
"Mmhm," Natsu hummed simply.
"It's…" Lucy debated with herself to continue. "It's so romantic, looking up at the stars like this."
Natsu's eyes drastically widened before a slight frown came to his features as he tried to determine Lucy's reason for telling him. Lucy didn't usually tell him about romance; she saved that for her talks with Levy.
Lucy finally turned to him again. "Isn't it, Natsu?"
"Hm?"
"Isn't it romantic here?" They both flushed darker.
"Sure," he replied simply, finding himself staring at her lips.
"This would be a…" Natsu heard Lucy gulp before continuing her sentence. "A wonderful place for a first kiss…"
His dad had tried to explain to him how to recognize when a girl was signaling to him, but the subtlety of it all had flown over Natsu's head.
But oh, Lucy was definitely trying to hint to him now.
What are you waiting for!? His mind screamed at him. Kiss her!
Lucy licked her lips.
Kiss her!
Natsu surged forward, knocking Lucy on her back as he leaned above her, taking her lips with his. Lucy didn't hesitate to respond, their lips moving against each other eagerly, as inexperienced they both were.
Lucy laughed when they separated for air, breathing heavily and playing with Natsu's hair as he pulled them up to sit. "About time you take my hints!"