“Well, that was fun,” Red Tie says after she’s gone. He’s smiling a big wide smile and looking at me with happy eyes. I get a sudden sense of déjà vu. I’ve been here before. I’ve noticed those bright eyes and that smile. I’ve even had this conversation.

But then the moment passes.

He sticks out his hand for a shake. “Daniel,” he says.

His hand is big and warm and soft and holds on to mine for a little too long.

“Nice to meet you,” I say, and take my hand back. His smile is nice, really nice, but I don’t have time for boys in suits with nice smiles. I put my headphones back on. He’s still waiting for me to tell him my name.

“Have a nice life, Daniel,” I say, and walk out the door.

Would-Be Casanova Shakes Cute Girl’s Hand, Offers Her Home Loan with Reasonable Interest Rate

I shook her hand. I’m wearing a suit and a tie and I shook her hand.

What am I? A banker?

Who meets a cute girl and shakes her hand?

Charlie would’ve said something charming to her. They’d be having a cozy coffee someplace dark and romantic. She’d already be dreaming of little half-Korean, half–African American babies.

OUTSIDE, THE STREETS ARE MORE crowded than before. The crowd is a mix of tourists who’ve wandered too far from Times Square and actual working New Yorkers wishing the tourists would just go back to Times Square. A little ways down the street, I spy Rob and Kelly. I stand there staring at them for a little while. She’s crying, and no doubt he’s trying to explain that he is not an unfaithful, disloyal jerk. I have a feeling he will be successful. He’s very persuasive, and she wants to be persuaded.

He and I sat next to each other in AP Physics last year. The only reason I noticed him at all was because he asked for help on the isotopes and half-lives unit. I’m something of an overachiever in that class. He asked me out to the movies after he passed the following week’s quiz.

Coupledom was new to me, but I liked it. I liked meeting at his locker between classes and always having plans for the weekend. I liked being thought of as a couple, and double-dating with Bev and Derrick. As much as I hate to admit it now, I liked him. And then he cheated. I can still remember feeling hurt and betrayed and, weirdly, ashamed. Like it was my fault he cheated. The thing I could never figure out, though, was why he pretended. Why not just break up with me and go out with Kelly instead?

Still, getting over him didn’t take that long at all. And that’s the thing that makes me wary. Where did all those feelings go? People spend their whole lives looking for love. Poems and songs and entire novels are written about it. But how can you trust something that can end as suddenly as it begins?

THE HALF-LIFE OF A SUBSTANCE is the time it takes for it to lose one half of its initial value.

In nuclear physics, it’s the time it takes for unstable atoms to lose energy by emitting radiation. In biology, it usually refers to the time it takes to eliminate half of a substance (water, alcohol, pharmaceuticals) from the body. In chemistry, it is the time required to convert one half of a reactant (hydrogen or oxygen, for example) to product (water).

In love, it’s the amount of time it takes for lovers to feel half of what they once did.

When Natasha thinks about love, this is what she thinks: nothing lasts forever. Like hydrogen-7 or lithium-5 or boron-7, love has an infinitesimally small half-life that decays to nothing. And when it’s gone, it’s like it was never there at all.

GIRL WHO HAS NO NAME is stopped at a crosswalk ahead of me. I swear I’m not following her. She’s just going my way. Her super-pink headphones are back on, and she’s swaying to her music again. I can’t see her face, but I’m guessing her eyes are closed. She misses a walk cycle, and now I’m right behind her. If she turned around, she would definitely think I’m stalking her. The light turns red again and she steps off the curb.

She’s not paying enough attention to realize that a guy in a white BMW is about to run that red light. But I’m close enough.

I yank her backward by her arm. Our feet tangle. We trip over each other and fall onto the sidewalk. She lands half on top of me. Her phone’s not as lucky, and crashes against the pavement.

A couple of people ask if we’re okay, but most just make a beeline around us as if we’re just another object in the obstacle course that is New York City.

No-Name Girl shifts herself off me and looks down at her phone. A few cracks spiderweb across the screen.

“What. The. Hell?” she says, not a question so much as a protest.

“You okay?”

“That guy almost killed me.” I look up and see that the car has pulled over to the side on the next block. I want to go yell at the driver, but I don’t want to leave her alone.

“You okay?” I ask again.

“Do you know how long I’ve had this?” At first I think she means her phone, but it’s her headphones she’s cradling in her hands. Somehow they got damaged during our fall. One of the ear pads is dangling from wires, and the casing is cracked.

She looks like she’s going to cry.

“I’ll buy you another pair.” I’m desperate to prevent her tears, but not because I’m noble or anything. I’m kind of a contagion cryer. You know how when one person starts yawning, everyone else starts yawning too? Or when someone vomits, the smell makes you want to hurl? I’m like that, except with crying, and I have no intention of crying in front of the cute girl whose headphones I just broke.