She always places herself first.
Like any relationship, there needs to be give and take and there comes a point where you want to preserve the friendship rather than always get your way. Is it always her way or the highway? If you find your friend always makes everything about her, then perhaps you should rethink the friendship. If she always waits for you to crawl back and apologize you may want to break this pattern in keeping with the theme that you teach people how to treat you and not indulge the outburst.
You can’t count on her.
Part of being a good friend is being there for your friends when they need you and vice versa. When you are in need of a friend is your friend around or is she frequently otherwise disposed? You should be able to count on your friend being there for you and likewise she should be able to count on you.
She isn’t trustworthy.
Can you tell her something in confidence and know that it will go no further. Friends should be able to share intimate details of their lives with each other with an expectation of privacy, especially if you both have the understanding that it is private information. If you tell your friend something confidential then overhear gossip about yourself that only she and you knew, then you may want to rethink the friendship.
You’ve grown apart.
Some friendships can survive growth in different directions and others cannot. If you have a mutual respect for each other and genuinely want each other to do what makes them happiest, then you should be able to remain friends. If one friend still likes to go out and party and the other friend wants to settle down and start a family, you may not hang out as much but you should be able to remain friends because you recognize that you are just on divergent paths that may cross once again. Some friendships though are based more on the hanging out frequently and doing the same things. These friendships often alter and sometimes end once one friend opts to take a different route.
Keep in mind that when you do ‘dump’ a friend you want to be at a level so that if you see each other in public it is not awkward but there is a mutual respect for one another. Be clear with yourself and your feelings and try to avoid saying anything you could regret. Sometimes misunderstandings can just be cleared up with a simple and honest conversation. There are also times where you can just discreetly go about your life and let the friendship fade or fizzle on its own without a long talk. In the end it is all about being happy and content with your life and those around. If someone has you stressed or upset more than they have you smiling, it is probably best to move on.