Like a clothing trend, but for your personality. A certain persona that everyone wants to have. Usually happens with girls who want guys to like them.
First, all girls wanted to be perfect, then they wanted to be clumsy, then they wanted to be confident, then they wanted to have a lack of confidence, then they wanted to be normal, then they wanted to be happy all the time, then music was their entire life, and now they always want to be depressed and have issues.
Screw personality trends, JUST BE YOURSELF!