Alright, first off, well done for a first release, especially as a new dev.
As for improvements: I have a few things, and most of this has already been mentioned, but
1. Optional content needs to actually be optional. Personally, I'm a huge perv, so I played first playthrough with every choice a yes, and was not at all disappointed (please gib more content kthx), but people have preferences.
2. It would be nice if I could actually say yes or no to everyone, or at least mostly everyone (I get that cutting e.g. the sister out of the story might be difficult).
3. The renders are the usual for these HS style games, not particularly good, not particularly bad. I personally have no experience with graphics work (I'm a developer in my day job, not a graphics artist), so I have no clue how easy or hard that part would be to change. It's not ruining the game as is, so it wouldn't be my first priority regardless.
4. If you intend this as a long term project, some more story would be required, otherwise it's just porn, and I might as well watch a vid on insert favorite porn site here. The story would probably have to revolve around the fairie girl, to make sense, which means any magical concept you could come up with would work.
5. The English could use a bit of work, but it's not too bad. If you want, I'd be happy to proof-read a script for you. Not something I'd normally offer, but this game has potential!
All of that said, don't take any of this as anything except advice on how to improve. You have delivered great content, especially for a newbie. Please don't stop doing so.