I realize that the premise of this manga is to create funny situations between these two on account of the differences in personality, and that's how I'm going to read it. It's the basic conflict between an introvert and an extrovert, after all. But...
...I know a bit about what it's like to need alone time in order to recover from a busy day. If I experienced this type of situation IRL, I would try to sit down with miss Kouhai and explain that, as the senpai thinks, I do like spending time with her but not all the time. Sometimes I need to be by myself. Hopefully something could be worked out. She seems nice in moderate doses.