Tbh I’m not sure what the problem is. You opened her by pretending that you’re already lovers. She responded in a similar way, but took it further by putting you in a playfully exaggerated high value position of king. This certainly seems a positive response to me. At this point I would have gone along with the role play (something like “every king needs a queen”), but you broke the role play, challenged her, and lowered yourself from the playful high value position she put you in. However, again she’s mirrored your message by challenging you back. I’m not really sure what else you’d expect her to do. It’s not necessarily completely negative, as challenging like this can be flirty in itself, which is possibly how she may be seeing it. As for what next, I’m not the best person to ask as I’m very new to all this, but something like “Not yet 😉” and then immediately change the topic might be the best bet.