Right, I know that these two always get happy endings, and I didn't wanna ruin that, so I left the ending open, you can decide what you want to happen. For me, they don't get a happy ending. But that's probably because I'm cynical, or because I'm in a similar situation to lily, and I don't see my happy ending.
Anyway, the usual disclaimer and everything, anything that's recognisable isn't mine.

We're a story that never gets told, we're a daydream I'll never get to hold.

Lily laughed as looked up at the clouds, trying to decide what shapes they were. A deep laugh from beside her echoed in her ears, filling her with warmth. She turned onto her side, resting on her elbow. Her eyes followed the lines and curves of the man next to her, taking him in.
"Lil, don't stare. It creeps me out." Sounded from the man's lips as his hair turned blue.
"Sorry, Ted. I like your hair when it's blue. It's my favourite."
"I know." Teddy Lupin replied, closing his eyes to shield them from the bright sun.
Lily sat up, her eyes landing on the wide lake in front of her. They were lying on the grass in front of her house, and it was summer. Lily smiled as she realized their hands were intertwined. This must have happened without them realizing, a habit, she supposed.
"Teddy, can I ask you something?" Lily asked timidly.
"Anything." He said, sitting up and kissing Lily's bare shoulder.
"Why do you like me?" She said shyly.
"I don't."
Lily felt tears prickle her eyes, and stared at her feet. She felt Teddy lift her chin so that her eyes met his.
"Lily, I don't like you." Lily's heart sank even further. "I love you. I love you because you make me laugh. I love you because you always outsmart me. I love you because when I'm with you, nothing else matters. I can be careless again. I love your eyes. They're so bloody beautiful, Lil. I love that you don't try too hard with the way you look, yet you manage to look perfect everyday. Even when you've just woken up. I love every little thing about you."
Lily's breath hitched, and she leaped on Teddy. As they rolled over, Lily kissed every part of Teddy she could reach.
"Lily!" Teddy said loudly.
"Oh, Ted! That was the most wonderful thing you've ever said to me. I love you - I love you - I love you!" She exclaimed, laughing.
"Lily! Lily!" Lily's eyes opened, the rain on the window the first thing she saw.
'Dreaming again.' she thought sadly. She'd been having similar dreams about Teddy Lupin since she was eight years old.
"Lil?" The voice spoke again.
Lily turned to see her older brother, Albus standing beside her.
"Ted and Vic are here.'Say they've got some big news to tell us." he said, before walking through to the kitchen.
Lily lifted herself off the armchair and followed her brother, taking a seat across from Teddy and Victoire. The rest of her family were in the room, and the atmosphere was excitable and nervous.
"So, what's going on?" Lily asked after a moment's silence. She looked up, and saw Teddy's hair flash to blue momentarily. She smiled sadly to herself.
"Well, Theodore and I have some wonderful news!" Victoire exclaimed, flicking her hair. Lily rolled her eyes, she hated when Vic called Teddy by his full name.
"Which is?" Albus asked, pushing Vic to go on. But Lily already knew. Her heart fell to her feet. On Victoire's left hand, on her ring finger, sat a beautiful engagement ring.
"Vic and I are getting engaged." Teddy said quietly, watching Lily.
As shouts of congratulations and hugs were exchanged, Lily's face grew more and more pale. Her world was falling apart, and she had no way to stop it. Teddy pulled away from the hugs, and turned to lily, who was as still as a statue.
"Lily, are you okay?" He asked.
A tear fell down Lily's face as she looked up into Teddy's eyes.
"Teddy, you're so stupid sometimes. How could I be okay?" She asked, her Slytherin strong voice wavering.
"I don't understand, are you upset that I didn't tell you first? It's only a recent - erm - development."
Lily looked at him, and for a moment she wanted to laugh at his words, because they were so Teddy. But then reality crashed down on her. She wanted more than anything to be lying on the grass in the sunshine, turning clouds into shapes.
"I have been thinking about you for the last eight years, idiot." Lily dropped her voice to a whisper. "I'm in love with you."
She stood up, pushing her chair from underneath her, and turned on her heel. She walked out into the cold rain, leaving behind an oblivious family and a broken, blue-haired man, who's love wasn't as unrequited as he'd thought.

Review please.
I'm not sure I'm done with this; it could do with a sequel.