Green isn't her color.
That's just one reason (of many, assured) that Scorpius Malfoy came up with as to why him and the lovely Rose Weasley should not be together. Aside from the whole "Weasleys and Malfoys don't really get along and haven't for the past 10 generations or so."
But yeah. Green really isn't her color. Her eyes are blue, meaning that she looked like a horrible Christmas decoration when she wore green (not that she ever looked horrible. She can't. She's a true beauty; anyone with eyes would agree).
It's a pretty accurate metaphor really, because her red hair (symbolizing her and all her Weasley-ness and everything Gryffindor) clashed horribly with anything green (symbolizing him and all his Malfoy-ness and Slytherin). And everyone knows it's absolutely crucial to a relationship that the girl and the guy must match in terms of color. Rose Weasley does not match with green (He isn't sure if red is his color either. He is, after all, Slytherin to the core). End of story.
Except it isn't the end of the story, because if it is, then he wouldn't be here, mentally convincing himself not to love her. It doesn't convince anyone, really. Damn be it that she doesn't look good in green. It doesn't change the fact that she's still beautiful and amazing and intelligent and sexy as hell and downright terrifying when she wants to be.
And absolutely perfect for him.
Ok, maybe they're completely opposites. But hey, opposites attract right?
And damn do opposites attract.
She's your typical nice girl, who's supposed to find a nice and respectable boy (who's last name doesn't start with an "M"), date for several years, get engaged, marry and have 5 kids (She's a Weasley. Nothing less should be expected) and live happily ever after. It's a nice life, typical of any wizard, well planned out, and absolutely boring.
Few people can see it, but she craves excitement. She craves thrill. She craves change. She's fiery and passionate underneath the good girl facade.
He can see it. He knows she wants to break away from the mold. She wants to act upon her emotions and not worry about the consequences. She doesn't want the life planned out for her.
She's passionate, he's apathetic. She's hardworking, he's lazy. She's righteous, he's sleazy. She's fiery, he's passive.
They're completely different, yet they're the same.
They both want to break away from the shadow of their surnames. Live just as Rose or Scorpius, not Rose "My parents were Harry Potter's best friends and my uncle is Harry Potter" Weasley or Scorpius "My grandfather was a high-ranking Death Eater and my father tried to kill the most beloved headmaster of Hogwarts" Malfoy.
They both want to live up and exceed expectations, all the while being afraid that they're just not good enough.
Even though they haven't gotten along ever since they laid foot on Hogwarts Express (that's one mild way of putting it. Hated each other and never managed to have a conversation without wands being drawn and curses being flung—now that's more like it), sometimes Scorpius feels as if Rose is only person who gets him (And in the middle of night, when they manage to catch each other alone, they've shared conversations and secrets and stolen glances and maybe, just maybe, their hearts)
Screw it all. Be damned that green doesn't look good on her. Rose Minerva Weasley and Scorpius Hyperion Malfoy should definitely be together. It doesn't matter what other people think.
Besides, silver looks damn good on her. It's her color, after all.