So here’s the thing: Noah is choo-choo obsessed.

Airplanes and other things with engines are interesting, but the first word out of his mouth most mornings is choo-choo, and it is with sobbing reaches towards the choo-choos that we take him upstairs at night. He takes a choo-choo into the bath, in the car, in the stroller, to Sunday school, to have his diaper changed — absolutely everywhere he goes. When we drive past choo-choos, Noah gets superexcited, and when they’re gone, he whines for “more choo-choo?”

The only thing that can reliably distract Noah from a choo-choo is the sight of an actual airplane flying overhead.

Those of you who have known me for a long time may find this funny. Ironic, even. And you probably understand my vague, very low-level, unease with this particular obsession.

To the rest of you, it probably just sounds like a cute toddler obsession, which indeed it is.

But you see, once upon a time, I truly believed that I was going to get married to a man.

And that man was choo-choo obsessed.

His choo-choo obsession manifested itself a little bit differently than Noah’s — for example, he called them trains all the time, where Noah only does that about half the time. And he liked to read and write dense law review articles about choo-choo economics and legal issues. Noah only likes to read books with pictures of choo-choos.

And Noah’s paltry dozen actual choo-choos can’t even begin to compare with my ex’s 30,000 cars, mostly put together himself from modeling kits, and hand painted with a painstaking commitment to precise historical accuracy. Plus, Noah has never yet gone on a road trip for the express purpose of taking pictures of trains.

What they do have in common is the age at which the obsession began. You see, my ex has (or had) an audiotape of himself as a toddler. He didn’t speak any English, but even allowing for the fact that he was speaking in toddler Italian, the portion of the tape in which he talked about seeing a train is perfectly clear. That was one excited, train-obsessed boy. Who grew up to be one excited, train-obsessed man.

I truly believe that as “man hobbies” go, train obsession is about as innocuous as it gets. But I do have to admit two things: First, I didn’t miss the train obsession at all, at the end of that relationship.

Second, it feels a little strange to have this unexpected and frequent reminder of a relationship that was probably the most difficult of my life. Certainly it’s the relationship that cost me the most, and changed me the most. On the one hand, I love where I am in life, so I can’t really regret the journey. And the choo-choo man is a good guy. But it was the wrong relationship in so many, many ways, and I damaged so many of my friendships while I was in it.

So yeah, I wish Noah stayed all about the airplanes. But he’s not, at least right now. Right now, he’s all about the choo-choo. And I am all about supporting his interests. I guess the good thing is that if he stays train obsessed, I’m already familiar with the lingo and the supplies. Too bad for Noah, our house has no basement that could be converted in its entirety to a model railroad.