The smallish girl dawdled along the street, her hands shoved in the pockets of her dark purple hoodie that she seemed to always wear. Her long dark hair was hung down her back, moving as she walked, her face hidden by the shadow from her looming hood. A tall boy of sixteen walked besides her, his dark black hair died with the electric blue streaks that he said she had inspired. They walked hand in hand, each others pale figures interlinked just like their hearts. The pair seemed to fit together like a puzzle, each one completing another. As a pair of blue eyes met up with the soft brownness of their soul mate, a small private smile was shared. No matter what happened in their lives, they were their for each other, only a phone call away. The taller of the two stopped, pulling the girl into a tight hug, her head only coming up to his chest. “Y’know… I love you.” He said, planting a small kiss with the soft velvety lips she longed to reach out a touch pressed against her hair.
“I love you too Rex. I love you so much more than words.” There was a slight pause in her tone. “For ever and ever.” Her blue eyes flickered to the whitewashed house on the street. “You have to go.”
“I know.” He sighed, looking around the dark street.

Its based on me and my best friend. The way we feel about each other but the way it will never happen. How can I Write some more?

Well, maybe what you should do is write what the two of you felt afterwards, maybe the emotions of what you feel about this whole situation. You could write about the times you had together that were the best times and maybe what times were like afterwads. Do you see where I'm getting at or are you confused? I myself am a writer, though I haven't posted much on here, and I like to read what people write and tell them either how good it is or if they should maybe redo something, but that is rarely.

I hope this is helpful for your writing and it's something close to what you might be looking for.