Well I in contrary don't mind purity of our girl. She is younger then him and raised in a church, not knowing any other life. What do you expect? They don't even call it by name - sex, but use a supplementary term. They are just awkward teenagers.
To be honest, this is normal mindset taught in catholic classes at school in my country - Poland. It's of course stupid and nobody is buying it but it exists.
Also, just looking how the plot develops, she actually tries to open to him.