Most of the time they just write: "I love you." Or: "I miss you so much." They write every day, several times, for weeks, sometimes they also make calls, cheers to messenger services and internet telephony.
But how do you build a 1800-kilometer bridge with words when the worlds are falling apart because one has fled and the other is at war?
What does that do to the relationship?
How do you stay connected?
And how do you endure all this?
Julia Schaaf
Editor in the "Life" department of the Frankfurter Allgemeine Sunday newspaper.
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"It's very difficult for us," says Lena, "not because he's so far away, but because of the situation in Ukraine." Her husband Sascha simply couldn't talk to her about his experiences as a war reporter.
"When I ask about his work, he says: Please, not the work.
Rather tell me about you.”
A couple in their forties, she a lawyer, he a documentary filmmaker and now a war reporter.
Lena and Sascha have known each other since school.
“In normal life, without war”, as Lena calls it, her friends say she has it good.
Her husband loves her and she loves him;
because Sascha travels a lot for work, she also has time for herself.
Now that she is sitting with her friend Vika and four children in a strange apartment in Berlin-Zehlendorf, it seems like a bad joke.
"I said to myself, I can do it, and I can do it," says Lena.
"But when I start thinking about how long this is all supposed to go on, I start crying.
Because I don't know when I'll see him again."
The war bombs families apart and the sexes back to the stone age, at least that's how it seems at first glance: men become fighters, women save the children.
Because the Ukrainian government banned men of military age from leaving the country on the first day of Putin's attack, the majority of the adult refugees are female - according to the Federal Ministry of the Interior, 84 percent are women.
Archaic gender images, as the gender and military historian Karen Hagemann explains, have a long history in war: male combatants are contrasted with female civilians, defensive masculinity justified with the supposedly necessary protection of women and children.
But it's not that easy, says Hagemann, who teaches at the University of North Carolina at Chapel Hill - if only because of the comparatively high proportion of women in the Ukrainian armed forces.
Is the war in Ukraine forcing men and women back into traditional roles?
The historian Claudia Kraft resolutely rejects this thesis: “Something is being performed before our eyes that we think we know.
We think: women are weak, men are strong.
But these are very artificial ideas.
I don't believe that the war is a turning point that fundamentally changes gender relations," says the professor of contemporary history at the University of Vienna.