Right now, I’m finishing up my next book, Project Empty Nest: Now What? As someone who studies happiness, I’m fascinated by this transition, because for so many of us, it’s a forced reckoning of adulthood.

This massive change in our family life gives us an opportunity to understand ourselves better and steer a new course forward—which can be thrilling. We don’t have many opportunities to be shaken awake. Our children are growing up, and so are we. We are still making our souls.

In writing this book, of course I reflected on my own empty nest experience – or, I should say, my open-door experience. I’m reframing this transition from the “empty-nest phase” to the “open-door phase,” which sounds far more appealing.

Over time, I came to recognize that, for me, there was the great paradox at the heart of this open-door stage of life: I want my daughters to know they are essential to my happiness, and also that my happiness doesn’t depend on them.

One of my favorite Secrets of Adulthood is: “The opposite of a profound truth is also true.”

My daughters are the most important thing in the world to me, and also they are not the center of my world.

I need them in my life in order for my life to feel whole; and I refuse to be needy.

This is one of the great mysteries at the heart of love.