I would put a lot more weight on her choice to live with you (pretty good indication she likes you quite a bit) than on a quip she made in a single conversation. It’s very hard to make a relationship work if small things like this can destabilize things to the extent that you’re questioning marriage! Try to measure your relationship by zooming out a bit more and considering whether she seems to enjoy your company etc. If you’re very upset save the assessing for a time where you’re calmer and focus on something else for awhile.