A bit too vanilla for my taste while still being weirdly kinky but never fully? I don't know how to describe the feeling. Writing was dry, I would have liked it if emotions or sensations were more described, especially because the girlfriend felt bland, like an object, despite the clear affection and lack of dollification/objectification hints.
I would have enjoyed the possibility of picking a female or neutral first name for myself, and would have felt way better if her age wasn't specified (19 is just... way too young to be in 24/7 Ds).
Since the writing is what you worked on, I think it could benefit from some polish. Still, a good game for a very first try, I think you did the exercise well!
Overall, the pairing appears to work and the consensual aspect makes it wholesome.