Mio's parents are awesome!
If I was an adult dating a high-schooler I totally would do xxxx and xxx! Yuzuki your lost!
Eventhough Yuzuki wants to do those things with Mio, Yuzuki is a responsible adult. Yuzuki doesnt want to cause problems to Mio since she is still a minor. You just can't understand. Her parents doesnt know they have this relationship. As soon Mio turns 20(legal age in japan) she will be free to do what she can't do as a minor, and that implies to choose whoever she wants to be with, live with, and she wants to become.