It happened almost overnight. One day I sent my husband a text message at work to say that our son was doing something annoying with his voice. “Like, it sounds hoarse or something,” I wrote.

And then, three weeks later, that son’s baby voice was gone. He came into the kitchen, said, “Hi, Mom,” with a deeper, rougher voice, and just like that, my days of being the mom to little boys was over.

“It’s not over,” my husband, Dustin, said. “Lindell (our youngest) barely even has hair on his legs yet.”

Dustin’s joking didn’t stop the tears. In that moment, when my two oldest sons, Ford and Owen, began speaking with different voices and shaving before school, I sensed a seismic shift in our world that my husband had not yet tapped into. He was still living in a place where our boys’ lives revolve around our family, where going to church on Sunday morning is not an option, where the kids would rather play a board game with their dad than go out with their friends. He couldn’t foresee how that time was coming to an end.

Of course, part of that might be because Dustin doesn’t get on Facebook much. He doesn’t see the “On This Day” photos from two years ago — just two years ago! — when Ford and Owen still had baby faces, crowded teeth and thin, baby-fine eyebrows. He doesn’t see the photos of friends’ newborn babies and try to imagine how ours were ever that little. What did they sound like? What did they feel like when we carried them? What did they smell like?

If I think about it long enough, if I wade through the photographs and partake in Facebook’s version of Memory Lane, I remember all the pieces: Ford’s toothless grin, Owen’s unruly hair, Ford’s favorite Nike sweatshirt, and how Owen preferred sitting in my lap to just about anything else. But if I stay there too long, if I flip through the years of photographs, it feels like my heart will break with some version of grief that is yearning for a time that is no more.

Dustin doesn’t see any of these things often, and when he does, he somehow doesn’t dwell on it. “They’ve grown into great young men,” Dustin will say. “You should be proud of them.”

And I am. But my emotion is mixed with something else, something beyond long-gone baby smiles, and it’s something Dustin cannot understand.

Ford and Owen turn 16 and 14 this week. With Ford’s imminent adulthood comes a creeping sense that I’m no longer needed in the ways I was before. Both boys bristle when I smooth their hair. They put themselves to bed. They make their own lunch. And on more than a few occasions, I’ve overheard them talking about where they’d like to live when they grow up.

Just two years ago, having my boys live anywhere else besides at home was not on my radar. I was fretting over one son not making the Little League All Star team or the other one leaving his lunchbox at school every other day. I was running to the store for poster board or sitting in the bleachers during basketball games. My days revolved around who needed to be picked up where and when.

“You’re still running around picking up people and sitting in the bleachers!” Dustin says.

But soon enough — so soon I can see it on the horizon — my older boys won’t need me in a daily sort of way.

For my husband, due to our arrangement as me being the stay-at-home parent, this shift isn’t as impactful. He’ll still go to work in the morning, come home for dinner and watch football at night. His days revolve around his work, and that isn’t changing. My work has been raising three boys, and for the first time, I see that role coming to an end.

“Lindell isn’t even out of elementary school,” Dustin says in frustration. “And you’re a mom for the rest of your life!”

Dustin thinks I’m being melodramatic and sometimes unfair. His life will change, too, he says, when the boys are grown. But in Dustin’s daily life, his goal is to make himself indispensable to an organization until he no longer needs to work and decides to retire. In my daily work, my goal has been to raise three children in such a way that they leave when they no longer need me. It’s a job where being “fired” means you’ve done well.

For the first time, I understand that.

“Don’t let all of this steal away your time with Lindell,” Dustin says.

And he’s right. I look at him in the backseat, talking about Star Wars or baseball or what he’s learned in school. He still sits close on the sofa or holds my hand at random times. And I try to savor every word, every moment.

Because if Lindell’s older brothers have taught me anything, it’s that these days don’t last forever, and the memories will be my favorite.