Why do I argue all the time with my friend?

[eee]

He is a boy and I am a girl, and we argue like some old couple, but we are just friends. I never argue with my other friends, and I know that he never argues with his friends either. But then why do we always argue with each other? It's always over stupid things as well, for example he always gets angry at me for supposedly lying to him and then it just goes back and forth.