Quick drabble about what I think they talked about during that scene, to make up for the delay of the long fanfic:
"You know-" Gwen began, looking at the sunset before them "I've seen my universe's sunset a million times..."
Miles turned towards her, her lips curled into a small smile, her shoulders back and relaxed. Her blue eyes shone like diamonds against the bright sunrays.
She looked ethereal, and Miles tried to store her image in his memory forever. After two years of longing; after two years of endless nights looking at the window, hoping she would come through it, she was finally here. Beside him.
He wanted to pinch himself, though he was afraid if he did it it would actually be a dream.
When she spoke up again his eyes trailed up, and he realize he'd been watching her new suit. The changes were subtle, but they were there.
"...but I don't think I've ever seen one as beautiful as this one" she turned to him and Miles swore his heart skipped a beat. The warmth colors contrasted with her pale skin, and the pink at the ends of her hair looked too vivid, rather than the washed out pink it looked like when she arrived to his room.
He was sure this was what Gwen was made for. To be adored, to be admired. To be basking in the sunlight and warmth of his New York. He doubted anyone else's universe (or anyone else, for that matter) could appreciate her the way she was intended to.
"I don't think I've ever seen any as beautiful as this one either" he mumbled, getting lost in the deep blue of the ocean that her eyes held. He was sure that if he could, he would've drowned in them a long, long time ago.
Gwen laughed confused, before realizing what he meant "Oh" a shy chuckle escaped her lips and she looked away of what she told herself was embarrassment. Though, between me and you, it was more because she did not trust her voice to not croak if she told him he looked very handsome too.
And while words may have not escaped her lips to show her gratitude, her hand trailed just a bit closer to Miles. As if to say "It's okay, I'm never leaving you".
She knew that was a lie, but she let herself daydream and enjoy the last bit of sunlight covering the rooftops of New York. So she hid the pang she felt in her heart and instead relished on the quiet breath of Miles next to her and the sound of her heartbeat, and how it beat for the guy she loves.