Girlfriend treats girlfriend as a joke.

I don't think so. There must be a certain space between lovers in order to maintain mystery and freshness. Increase the attraction of each other. The relationship between girlfriends should be between the same sex. Personally, I think you think your girlfriend is gay or your girlfriend thinks you are gay. Or none of you have positioned yourself well. Such a relationship should be avoided as far as possible. When we get too familiar with each other, it will gradually become boring. Maybe you all like this relationship, so it doesn't matter. The key is how you feel.