What I didn’t tell you as you waved to me from the ferry that early September morning and left me, literally, watching from the pier, was that I was overwhelmed with a wave of grief the likes of which I first felt only after my mother died.

How sudden it has all been. When you were born I couldn’t imagine you growing up and assumed I would have you as a little boy forever; when you were in high school we were far too preoccupied with getting you into college; now that you are actually leaving, I am stunned. I am aware that I am over-dramatizing everything: neither of us is dying nor going to war, but it is hard nonetheless.

I keep wondering what I have forgotten to tell you, to show you. This is how my mother felt, only much more intensely of course, when she found out she only had a couple of days left to live. She had been living with a death sentence for two years but still thought she’d have more time, that this moment wouldn’t actually ever come. We spent those last days together and she tried to remember everything she wanted to be sure she had told me. Of course she already had, but I listened anyway and even humored her by taking notes. When she was through, she died.

What I didn’t tell you was that after you left all I saw were 14-year-old boys — those adorably gangly not-quite-men, those lanky boys, still carefree — not yet interested in girls nor too worried about their futures. I saw them everywhere, doing what you and I used to — skipping stones on the ocean, riding bikes, enduring annual back-to-school shopping trips. I saw those boys just as, before we had you, I saw only pregnant women.

Why am I missing you so much when you were 14, of all ages? Why not 3? 6? 10? I have never had trouble grasping that you were growing up, that you were evolving. Why then suddenly do I feel these unpredictable waves of grief over your passed childhood? You haven’t been 14 for a while — why is it suddenly hitting me that you will never be that age again?

Trying to explain this over the summer to you, the day-camp counselor, you commiserated. “I know. I feel so sad when I see that my adorable six-year-old campers have turned into obnoxious nine-year-olds.”

You have no idea, I thought to myself. Not that you have been particularly obnoxious. In fact, maybe this all would have been easier if you had been. You didn’t act out during the summer like other incoming college freshmen; you didn’t spoil the nest so that we were secretly happy to see you go. No. In fact, in June you and I discussed how we were not going to fall into the trap of arguing and deliberate distancing before you moved away. Rather, we consciously decided to be cool and separate gracefully, like grownups. Maybe this was our mistake: maybe we skipped a necessary phase of development.

So I didn’t let you see me cry from the boat, and didn’t tell you how I made it as far as the kitchen table before I put my head down and wept.

Older mothers assure me that my bittersweet pangs will be replaced by pride at your independence, and that you and I will forge a new relationship as two adults. They tell me I have no inkling of the joy I will feel when you have your own son.

I am sure this is true. But I loved our old relationship, as mother and boy, and I miss it. We were so lucky, so happy, so carefree. So what I must remember to tell you now, borrowing a phrase from The Giver, one of your favorite books from Middle School, is this: thank you for your childhood.

Holly Eger lives in West Tisbury.