a lot of chapters I find it dull. for me a erotic game is about pushing the boundaries, to be surprised, to focus on the eroticism and emotions of the characters. sure, not all erotic games need to be like that, but a visual novel is for me that, a visual erotic novel with options to have different routes. so its not a game or a simulation but a multi choice novel.
I cant feel the emotional closeness between F&D, its superficial, where a lot of times the Mc is egoistic that from time to time act like he need to be mature and understanding, but later show his true colors when he act like a young boy or detached.
D is naive and sometimes stupid, and not always I find it attractive that she is like a child but annoying when shes no reacting like a 18 years old should.
in my mind, a father that gets close to his daughter like that (I try to not moralize here) would not want to be with another woman, and it would make more sense that he focus on her "sexual training", I mean, theres a lot a couple can do.
toys, bdsm, voyeurism, private photoshots/video, fisting, erotic massage, g-spot, facials and deepthroat and so on. also, we have the "mind and emotions", to talk dirty, share fantasies, push each other with suggestions, well, a lot can be done that dont need to introduce the same boring sex scene with another pixel-model.