I've already told you all the good reasons to break up with your boyfriend or girlfriend, which pretty much include everything. But there are some bad reasons to break up, too. If you're ready to dump your sweetie, check this list first and make sure you're not doing it for the wrong reasons.
1. You're Just Trying to Make Him Mad
Or you're just trying to make him jealous, or to make him like you more. That's just a silly game that suggests you're not mature enough even to have a boyfriend. If you've got something to say to him, come out and say it - don't try to trick him by doing something you'll probably regret later.
2. You Got Into a Fight
Fighting part of dating. (Verbal fighting, that is. If it gets physical, get help.) If you can get through the argument calmly and reach a solution that you can both live with, then it's a reason to stay together, not to break up.
3. Someone Else Wants You to Break Up
If you're feeling pressure to break up with your girlfriend, talk to her about it - and if you're getting bullied, get help from an adult. But don't let anyone get their way just because they're being a jerk. (Though if all of your friends agree that your relationship is bad news, they probably have a point - see #6 in the reasons to break up.)
4. You Have a Little Crush on Someone Else
If you've just got a little crush, and you haven't had it for very long, wait it out and see if it develops into a big crush. There's a good chance it might fade away, and you'll be glad you didn't do anything drastic.
5. You Like Different Stuff Than He Does
You shouldn't spend every waking minute with your sweetie. The fact that you have different interests and want to spend your day doing different activities is a good thing, not a bad thing. Quit panicking about your time spent apart, and use it as an excuse to hang out with your friends more.