Honestly, this is murkier than people admit. The obvious stuff applies—don't plagiarize, get proper consents if you're using a real person's likeness or backstory, and definitely avoid anything illegal. But the grey area is intent. If you're using it to brainstorm tropes or overcome a descriptive block for a consensual scene, that feels like any other writing tool. The problem starts when the entire creative voice, the human understanding of intimacy and vulnerability, gets outsourced. Readers can tell. Erotica that lacks that specific, flawed, human spark just reads like technical documentation. I tried generating a few passages once out of curiosity, and the phrasing was technically proficient but emotionally vacant. It nailed the mechanics but completely missed the point of why people read the stuff. The ethical guideline, then, might be about transparency. If the AI is doing the heavy narrative lifting, should that be disclosed? Probably. But the industry has no standards for that yet.
Another layer is the training data. Most models are trained on vast scrapes of the internet, which includes a ton of erotica posted without the original authors' knowledge or permission. So even if your prompt is original, the style is being built on uncredited, possibly uncompensated work. That sits uneasily with me as both a reader and someone who dabbles in writing. It feels extractive. My gut says using AI as a pure idea generator or editor for your own drafted work is the least problematic path. Let it suggest synonyms for 'throbbing' but don't let it write the kiss.