Ending a long term relationship with someone you thought you would be together with forever is one of the hardest things to do. Even though its hard, that doesnt mean it shouldnt be done with class and maturity. Not only is it an immature thing to do, but having a rocky breakup also creates other issues. The more is costs, the more it damages you both and the longer it takes you to move on are just a few. You also want to make sure to be the bigger person. Do it in person, dont tell anyone and everyone, and always make sure to not look back. The more mature you are about a breakup, the happier you will be in the end.