The adult who is constantly changing jobs and changing mates is immature. Maturity is the ability to control anger and settle differences without violence or destruction. The mature person can face unpleasantness, frustration, discomfort and defeat without collapsing or complaining. He knows he can't have everything his own way every time. He knows when to compromise and is not too proud to do it.
Maturity is humility.
Maturity is the ability to live up to your responsibilities, and this means being dependable. It means keeping your word. Dependability is the hallmark of integrity. Unfortunately, the world is filled with people who can't be counted on. When you need them most, they are among the missing.