There is, of course, no single explanation, and I listed a number of possible explanations: "Increased use of illicit drugs and prescription drug abuse, and less human interaction because of constant cellphone use are two widely offered, valid explanations. Less valid explanations include competition, grades anxiety, capitalism and income inequality. And then there are young people's fears that because of global warming, they have a bleak, and perhaps no, future."
But I do believe that a loss of values and meaning are the two greatest sources of unhappiness.
Among the values lost are those of communal associations. As the great foreign observer of early American life Frenchman Alexis de Tocqueville wrote in 1831, Americans' unique strength derived largely from their participation in innumerable nongovernmental associations ‐ professional, social, civil, political, artistic, philanthropic and, of course, religious.
But these have all dwindled as government has become ever larger. Whereas Americans got together and formed bonds of friendship through nongovernmental associations, through what organizations will Americans form friendships today? In a video presentation at its 2012 national convention, the Democratic Party offered its answer: "Government's the only thing that we all belong to," the narrator said.
Then there are traditional middle-class values, like getting married first and then having children. Today, a greater percentage of Americans are born to unwed mothers than ever before, and fewer people are marrying than ever before. There are, for the first time in our history, more single Americans than married Americans. While it is certainly possible to feel lonely in a marriage, people are far more likely to feel lonely without a spouse, and increasingly without children, than with a spouse and children.