We all grow and change constantly. The big thing with a marriage relationship is growing together in such a way that the new people you are constantly becoming remain compatible.

In most cases you or that other person don't cease to be the people you were six months, a year, or five years ago. You are still that same person with some additions and subtractions. You let go of pieces of you that no longer fit and gain ones that do. It's a constant evolution. In a lot of ways it's like molting. You slough off the skin you've outgrown, but you never stop being you underneath it.