Excellent article at Giant Impact on how the group U2 has managed to stay together for so long. Here is an excerpt:
The bedrock of any team is the relationships between its individual members, and U2 are no exception. Certainly, the four self-assured showmen have had their artistic squabbles and personal conflicts. Yet, the mutual respect shared by the members of U2 has enabled the band to remain intact after 30 years of making music together.
Ask U2 about the band's internal dynamics, and they'll invariably point to the metaphor of marriage. In the words U2's guitarist and keyboardist, Edge "I'm so close to the other three guys in this group that sometimes it feels like a marriage."1 Drummer Larry Mullen Jr. agrees, "We don't always like each other but we respect each other, and we love each other. Marriages don't last this long."2 While U2 may have their rocky moments, at the end of the day any disagreements between them pale in light of their committed friendships.