Why did she leave? I mean i am a really nice guy but i seem to be rejected by the way i look does anyone have any pointers,

Your first mistake is assuming that you're a nice guy. You might be one, I'm not saying that you're not... but girls usually don't like overconfidence/egotism. If she's a nice girl, she doesn't care about your looks, more of the kind of person you are. Be nice. Be loyal. Show her that she's valuable and precious... make sure she knows that she's the most important person to you. Treat her like a queen. Give her your time, don't ignore her for your video games... girls like it when you show that they are more important than the games. And if she still leaves you, don't be sad because that means she doesn't deserve you...you deserve better!