一凹一凸

When we are young, we can be molded to fit each other fairly easily. Even if we don't fit perfectly, we are pliable enough that our rough edges can be rounded and ground out without too much pain. Think of ourself as clay. As we dry out and get older, we can no longer be shaped into different forms easily. We settle into a rigid self.

To find the second half that fits.... is not easy any more.

But.... water. As long as the clay has not been fired before. You add water. You get back the workable clay. Yes it will take time and lots of hard work. But as long as you add enough water and with patience, your clay can be reshaped again.