Hey tidbit. This is tricky to answer, if I'm going to be honest. Can we have further clarification on how the human will play a role in your story, if any?
If he's essentially treated as a side character whose sole purpose is to keep the parasite alive and the romantic focus remains entirely on our parasite, I think we can allow it. But again, let me know what you plan on doing so I can give you my final final answer!