There is no etiquette here yet. The technology arrived faster than any shared sense of what it means, which is why the question feels loaded out of proportion to the activity.
What follows is not a rule. It is the small number of distinctions that make the decision easier.
The test that settles most of it
Forget whether it is "cheating" or "weird" in the abstract. Those arguments have no resolution and people mostly use them to reach a conclusion they already had.
Ask instead: would I be comfortable if this were found rather than told?
If the answer is yes, you are using a piece of software and there is nothing to disclose. If the answer is no, the discomfort is information — not necessarily that you are doing something wrong, but that you have decided it means something you have not said out loud.
That single question resolves the partner case more reliably than any argument about categories.
If you have a partner
The strongest reason to say something is unglamorous: discovery is worse than disclosure, every time. A phone left unlocked, a lock-screen notification, a line on a shared bank statement. The practicalities are in payment privacy and using a shared device, but no amount of setup removes the risk entirely.
If you do raise it, two things help:
Lead with what it is, not with a defence. "I've been using one of those AI chat apps, it's a bit like a game" starts a conversation. An unprompted explanation of why it does not mean anything starts an interrogation.
Expect the real question underneath. It is usually not about the app. It is "is something missing?" — and it deserves a real answer rather than a reassurance about the technology.
Sometimes the answer is yes, something is missing. That is worth knowing and it is not the app's fault.
If it is friends
Lower stakes than people expect. The most common reaction is curiosity — "what's it actually like?" — because most people have read about this category and never tried it.
A short honest framing does the work: it is entertaining, it is a bit like a novel you talk to, and it costs about the same as a streaming subscription.
The people who react badly are usually reacting to a picture of loneliness rather than to you. That is worth its own consideration, but it is not a reason to lie.
At work
Do not.
This is not about stigma, it is about what employers can see. A work laptop is managed hardware, the network is monitored, and none of it is your business to argue with. Keep it off employer devices entirely — the reasoning is in using a shared device.
Words that help
Describe the activity rather than the relationship. "I use an AI chat app" lands very differently from "I have an AI girlfriend", and both are accurate. The first invites a question; the second invites a judgement.
And say what you get from it in ordinary terms — it is relaxing, it is fun to write with, it fills a quiet evening. These are unremarkable reasons to do something, and framing it as unremarkable is usually honest as well as effective.
Where the honest discomfort lives
One case is worth separating out, because being straightforward about it is more useful than reassurance.
If you find yourself not wanting to mention it specifically because you know you are using it instead of something — calling someone back, going out, dealing with a thing — then the reluctance is pointing at the substitution, not at the app. That is the signal the boundaries piece is about, and it is a better thing to notice early than late.
Most people are not in that case. Most people use one of these apps a few evenings a week and the only awkwardness is a conversational one, which fades fast.
The sentence that usually does it
"It's a chat app with a character, it's good for switching off, and I'd rather you heard it from me than found the subscription."
Direct, unapologetic, and it makes clear you thought about them — which is generally the entire content of what is being asked.
