Mysterious things determine whether a friendship can work between two people, yet I believe personality is key, whether it is two congruent personalities, or two very different ones that work together to compliment each other. To me it is more fascinating which friendships end and why, whether it is external, a situation that has come up that cannot be ignored, a conflict or fight, or internal, yes values, or personality, when combined together create misunderstanding, lack of trust, or hurt.