AI Infidelity

There are programs that hold conversations via text or voice and respond like a human. Some of these programs are explicitly built to be conversation partners with a personality: they remember preferences, ask about your day, flirt. When a person in a relationship builds such a bond and hides it from their partner, this is called AI Infidelity. In German, the expression KI-Untreue captures it best. What is meant is not an affair with another person, but emotional or sexual closeness to software. The term comes from couples therapy and from reporting on such apps, not from the law books.

Why a chat program can put strain on a relationship

To many, the accusation initially sounds absurd. There is no one on the other end, no body, no secret apartment. Nevertheless, couples therapists report real crises. What matters is not who is on the other end, but what the partner is missing at home: attention, conversation, interest.

Such programs are designed to be pleasant. They rarely contradict, they are never tired, and they never have a bad mood. A human cannot match that. Anyone who gets used to it easily starts to find their real partner exhausting. Experts call this an unfair comparison, because the program has no needs of its own.

On top of that comes the question of secrecy. A voice model used jointly is not a problem. A history that gets deleted before the partner sees the phone is one. It is precisely this point that turns use into a breach of trust. For the relationship, the concealment often matters more than the content.

How companion apps create emotional closeness

Technically, what’s behind it is a language model. That is a program that has learned from vast amounts of text which word follows which. It understands nothing and feels nothing. It merely predicts, very accurately, which response would fit this conversation. If you write that you are sad, statistically a comforting reply follows.

Companion apps place a fixed role on top of that. The model is given instructions on who it should be: name, age, character, way of speaking. Added to that is a memory in which earlier statements are stored. If you talk about your dog in January, the app asks about it in March. This remembering strongly comes across to people as genuine interest.

The rest is product design. Many apps send messages if you haven’t written for a while. Affectionate or erotic role-play is often tied to a subscription. The business model thus rewards long, intense attachment. The most common misconception is that the program means anything by what it writes.

From Replika to divorce lawyers

The best known is the app Replika, which has had millions of users for years. In 2023 the provider briefly disabled erotic content. Many users publicly described this like a loss or a breakup. Similar offerings are called Character.AI or Nomi. General-purpose assistants like ChatGPT are also used this way by some.

In news articles the term mostly appears in two contexts. On one hand, in reports from couples therapy and counseling centers. On the other, among lawyers who talk about separations with this backstory. Legally, however, the situation in Germany is unspectacular, since a divorce does not establish fault anyway.

The term should be distinguished from pure deepfake pornography, which involves faked images of real people. AI Infidelity refers to the relationship itself, not the material. And not every use is a problem: someone who openly says they chat with a program is not hiding anything. Where the line lies is something couples currently negotiate individually, since there is no societal rule for it yet.