"tired of her"
Wait, so you were just "using" her like that? [No love/feminism jokes, please], that's the only reason given and you want to jump to get another girlfriend?
Serioulsy, that's a dumb move, you can't just hop over to another girlfriend whenever you feel like it, stay with her for a while, do something with her to make the bond stronger, but if you seriously need another one like that, be honest.