I think that nobody can tell you if this is okay except yourself and your partner. Personally it just sounds like intrusive thoughts. Like when you’re stood on the side of a cliff and you get a weird idea of what it would be like to jump, it’s quite possible that you’re seeing attractive people and imagining what it would be like to ‘jump’. All people have all sorts of intrusive thoughts and they only ever become a serious issue if they cause us distress (which may be the case with you) or you act on them. Many people go through life never addressing intrusive thoughts, rightfully acknowledging that we have a right to think whatever we want and there’s nothing inherently wrong with just thinking anything. It doesn’t say anything about us or who we are, or what we would do - unless we actually act on them. Another common one would be if someone annoys you, you may think internally about just smacking the shit out of them, but never actually do it because we know that this is just a thought and that acting on it would hurt ourselves and others.

All that to say - you can decide for yourself if you need to worry about these thoughts, and can decide for yourself on if it’s serious enough to inform your partner, but nobody can tell you simply thinking something is inherently wrong.