As a friend, you do your best to love and support someone. This love and support can only go so far when a person continually makes bad choices and goes against the advice they seek from you. From what we've seen, Taylor has done her best to stand by her friend. By returning to the relationship, Selena has made yet another poor choice. Taylor has the right to wash her hands of the situation rather than deal with the expected drama.
Yes, Taylor Swift was right to end her relationship with Selena Gomez, because Selena Gomez was not much of a friend. Taylor Swift has a lot of self confidence. She is what we all want to be in that respect. For that reason, Taylor Swift was right to kick to the curb Selena, who was not being a real friend.
I couldn't care less what Taylor Swift, Selena Gomez, or Justin Beiber does. I believe celebrities should be role models and not one of these people have even made a decent attempt at being such. I think these people are talent-less and their careers are upheld by the companies who profit off of them.
Taylor Swift absolutely should not have ended her friendship with Selena Gomez over Justin Bieber and Selena Gomez's relationship. Friends shouldn't have a falling out over who one of the other parties are friends with. Taylor Swift should make up with Selena Gomez because it is the right thing to do.