the best way to end a relationship, but we can always try to make the separation easier to accept.
Paul Simon had a song, "50 ways", but there are never 50 ways, especially when you want to end a relationship. If you are very nervous and you argue a lot with your partner, then the break up will arrive immediately, without any sufferance, maybe just some anger. But if you had a long relationship with someone and it just doesn't work our anymore, you care a lot about that person and you don't want to make her cry for you. There are no special courses in which you can learn how to leave somebody, you'll just have to do that and it depends on you how is going to end.

Experts say that the best way to end a relationship is to look after you first of all. And this is true! If you feel unhappy, you should reconsider your thoughts and your feelings about the other one. Sometimes, you just have to be a little more selfish and to think about yourself and to put your partner on the second place. But before that, you should face your problems and your couple issues, without any fear. Accept the real situation and try to find a way to solve it, without being pessimist. Actually, this contributes a lot in choosing the best way to end a relationship: you should think positive! You will find another person and you will be in love with her, and your partner will find someone else too! The world doesn't end with you two!
Therefore, while talking with the other about your relationship, try to be calm and to explain things as clear as possible. Don't get angry and try not to yell, no matter how your partner would react. Try to give him or her the main reasons why do you want to separate and try to end up in a friendly way.
And as a further advice, don't be afraid to fall in love again! You never know where or when you could meet your true soul mate. Just try to stay away from vicious, unhealthy and boring relationships!