Villains are for comic books. This wouldn't make sense in real life; you don't start a relationship with someone you are attracted to by immediately getting into a fight with them.
No, the eventual lovers fight—to a draw—because deep down they are afraid to love. The Writers Store eZine. First, love is the only genre where you need not one, but two equally well-defined main characters.
Third, love is a story form that should naturally take ten minutes. Remember, in the best love stories, the deepest opposition to love is love itself.
Also, all the talk of not being able to write a romance scene without having lived one seemed a bit off to me. It's not easy. But then obviously along comes a sexy new boy and she makes the most ridiculous comment about him being the only boy of her age that she might stand a chance of being interested in.
Besides, it's a lazy form of writing - a kind of shorthand to communicate rage, frustration or in some cases, an evil character. From what I read, I enjoyed Tilly's relationship with her grandma.
Now we've all had our scars from love, but making one of your characters emotionally crippled from a single affair of years gone by is silly.