I feel like this is a pretty common problem in adult vn games.All of them are a bit childish for their age. The redhead is the worst. Yes, she comes from an all girls school and has have a sheltered life, but she talks like if she were 14 or 15 more than 18 and seems to be really naïve
And personally, I find that usual 'naive virgin' girl the most uninteresting of the bunch.. and they usually give bad vibes and make me question the devs intentions.