It's pretty easy to misunderstand things when two people are talking but have different ideas in their heads, this is also a thing that happens in manga and anne often because of how context heavy Japanese is, they each have a different context for the conversation but it keeps going because their are continuing it with their own context in mind.Especially for an adult woman. You're kissing, dating, and living with your GF. What adult woman (Japanese or not) wouldn't understand what that means in this day and age? Her specific issues seem beyond silly, even for a manga. A setup like this is normally used as a joke, not something to be taken seriously.