File photo: I couldn't understand why he engaged so intensely and then suddenly and coldly disconnected. Picture: Supplied

On a hike in the Hudson Valley with my cousin a few weeks after getting dumped, I laid out my theory: He was a CIA/KGB double agent.

We met during Hanukkah, and it was over by Passover the following spring. Human nature hard-wires us to make sense of what happened at the end of a relationship, to go back to look for clues and solve the mystery of why someone no longer wants to be with us. I told myself that he ended things not because he wanted to but because his handler realized I was becoming a liability.

We matched on JSwipe in November. He was an American diplomat doing a year of language study in Washington before his next posting in Japan. He pursued me, sending a flurry of texts in the weeks before we met. This made me, a veteran online dater, skeptical. I figured that, by the time we finally met, I wouldn't like him. But I did.

Early on, he asked if his professional lifestyle was one I could envision myself sharing - he had just returned from a dusty year in the Middle East and three humid years in India. I unflinchingly said yes. My family had lived in Asia and Latin America; life abroad was familiar and appealing to me. "Would you go with me to Mogadishu?" he asked, "Yemen?" "Kabul?" Perhaps the locations should have been a giveaway.

I was falling for him, but I still had questions about who he was. He said he worked for the State Department, but did he really? "He's a spook," my friend Jon said after meeting him once. "I can just tell."

Jon wasn't the only one with the spy suspicion. After an extensive Google search, my father, concerned that I was unusually besotted with this tall, Midwestern stranger, came back with almost nothing. There was just one arbitrary quote in a college paper. No LinkedIn profile, no stray charity fun run donation, no professional research contributions from a pre-government job. Plenty of people keep a low profile, but in our generation, being a total nonentity online is curious.

There were other subtle red flags, like that he would pick me up from the bus in a different rental car every time I visited. He assured me it was easier than leasing a car, because he was only in town for a year. Maybe that's true. Or maybe he didn't want his whereabouts easily tracked.

Another red flag: He was easy to talk to, except when it came to his past. On former relationships he would give me information as if we were in a deposition - one-word answers, time frame, place it happened, but no context. "Why are you asking?" he countered evasively. I wanted to better understand his emotional history, but I let it go.

In retrospect, I figured that this ability to be tight-lipped probably served him well when being trained to resist enemy interrogations.

One night, I confessed I had fallen in love with him. I didn't need him to say it back. But instead of telling me how he felt, he just warily replied "Oh. ... Have you ever felt this way before?"

I could feel the pain start to radiate. "Do you at least care about me?" I pressed.

"This just isn't fun anymore," he responded.

Three weeks later, he took me to a Washington Nationals game and bought me a Bryce Harper T-shirt. During our goodbyes he said: "So I'll come to New York next weekend. We can go bike riding in Central Park, if that's not too cliche?"

When a relationship ends abruptly, we often look for reasons why. We craft stories of psychopaths, narcissists, alcoholics or, in this case, international espionage to guard against the painful possibility that someone might have not been that into us.

I couldn't understand why he engaged so intensely and then suddenly and coldly disconnected. I decided that the only explanation was that he was part of an intelligence agency operation. That his relationship with me had been a convenient cover; a girlfriend would make him look innocuous. This theory made me feel less like a chump. Then I didn't have to entertain more everyday hypotheses like he discovered something about me that was a dealbreaker, or he was an ordinary 30-something commitment-phobe, or maybe there was someone else more appealing.

It hurt less to think that he was instructed by a superior to end our relationship and was just following orders.

Ultimately, he probably wasn't a spy. But maybe he did with me what he has trained to do professionally: He engaged deeply; acclimated himself to the culture; learned my language; got to know the key players; made everyone feel comfortable and special. And when it was time to go, he detached to move on to the next assignment.