Levine is the Huffington Post's "Friendship Doctor," a psychologist, a journalist, and a professor at NYU School of Medicine. Men, jobs, children, personal crises, irreconcilable social gaps — these are just a few of the reasons that may cause a female friendship to end. "No matter what the circumstances, the breakup of a female friendship leaves a woman devastated and asking herself difficult questions," she writes. "Was someone to blame? Is the friendship worth fighting for? How can I prevent this from ever happening again?"