When my expat friend of 12 years moved away, it broke my heart. It taught me how valuable friendships with other expats are.

• I'm an expat, and have been living in Germany for 14 years.
• During my time here, I've realized how important friendships with other expats can be.

In my almost 14 years of living in Germany, I've realized how meaningful friendships with fellow expats can be. Most of us have an ocean separating us from our friends and family back home, and when you live in a country where the dominant language differs from your mother tongue, speaking the same language helps speed up any relationship.

And when a close friend you've made in your new locale moves away, it can hurt like a breakup. That person is embarking on a new adventure, while you're still in the same place, without the heartfelt connection you've spent time building.

It hurt when my expat friend of 12 years moved away

In a survey of Dutch adults cited on an NPR podcast I recently listened to, 70% of respondents reported their adulthood friendships lasting about seven years. My friendship with Zoë has lasted far longer than that — more precisely, we've been friends for 12 years and six months. For the first 11 ½ years of that friendship, we lived in the same city in Germany.

Last year, Zoë and her family relocated from Germany to Spain — two hours by plane, then a 40-minute train ride, and, finally, a long ride in a car. While I can always visit her (and I have twice), she's no longer a 15-minute walk from my door.

I miss the impromptu weekend outings we went on together and our spontaneous walks around the park. Her absence still feels fresh and overwhelming, and I've grieved over it.

During my time in Germany as an American expat, I've tried to protect myself from being too close to people staying a short time, and I've spoken to fellow expats who feel the same way. There's an almost universal rule about making friends. Whenever you meet someone, the question always arises: "How long are you staying here?" How that person responds can determine whether the conversation, or friendship, will continue.

While some people stay a few years in one place before leaving — and it's always difficult when someone you've become fond of leaves — it's probably even worse when a friend of over a decade has a change of address.

We connected on common interests

I met Zoë in 2011. We never asked each other the question since I naively assumed we were "lifers" in Cologne. Though I discovered she had lived in quite a few places, she particularly enjoyed Cologne and its cultural offerings, and I thought she was here to stay when she gave birth to her first child.

We met online when I tried to get a craft group off the ground. One evening, she replied to one of my posts about meeting up. As it turned out, three others also expressed interest, so we established a group. For our first session, we met at a café near the University of Cologne, and we continued to meet there every Wednesday night. It was dimly lit with frayed, vintage furniture and good energy.

As the first members of Crafty (what we called our group), we got along well and enjoyed our time together. After a few months, Zoë and I were on another level of connection: We exchanged texts before we did with the other Crafty members to ask whether the other one would be at a session. If I knew she was skipping that week, I would be less inclined to go and vice versa.

Zoë hails from England and her husband is from New Jersey. We immediately hit it off during our initial IRL meeting: She was wearing a slim-fit WFMU radio station T-shirt, displaying her great taste in music. She first struck me as American, but every time she opened her mouth, she spoke with an English accent. I later learned she earned a higher degree from Oxford University. I found this impressive. She was a teacher at an international school and once told me its director modeled the environment after Hogwarts from "Harry Potter."

Both of us naturally connected on several topics: our love of music, film, crafts, fashion, traveling, exploring Cologne, cooking and eating food, and supporting each other. Of course, it also helped that English was our first language (even though we spoke it with different accents). I don't think I could have survived my pregnancy, the birth of my child, and my subsequent miscarriages if she hadn't been around.

I value our friendship and miss her dearly

I love her more than I've ever loved any friend; even using the term "best friend" does not feel like enough to describe our connection. As another expat friend told me, "Women friendships are the real love stories."

We went on a couple of family vacations together. Her sons and my child were like blood siblings and have known each other since birth.

I knew I could go to her for everything, and I did. We've always texted each other freely whenever, and about whatever: photos, memes, short and funny messages, and sometimes longer, more heartfelt content. We still do this.

Then last year, she did the unthinkable. She told me her husband was inheriting enough money for them to buy a house — their family was outgrowing their two-bedroom apartment. Though they wanted to stay in Cologne, the market here was impossible for their parameters. They searched farther afield: Amsterdam, Berlin, and coastal Spain.

In the end, Spain won one of the best families.

We said goodbye to each other on the Monday evening before her Wednesday flight. I don't think we ever squeezed each other tightly like that before. Is there any way to say farewell that equals how you feel? We would have been there forever.

Still, I'm nursing some hope that I'll meet other friends and form similar deep connections. At this phase, it seems unlikely they'll match our extraordinary friendship.