OK, I'll address your concerns one by one.
Re: More choices: I've written this to be a kinetic novel all along. I put in those choices to appease the "more choices = better" crowd.
Re: More romantic sequences: Hmm... due to the time limits, I didn't emphasize those sequences to show how lovey-dovey the couple are. I may have to address that in the next update, which will be released next month.
Re: The ending: Yeah, I admit it's an abrupt twist. I may have to address this too in the next update.
Re: BGM and SFX: They're already credited in the in-game credits sequence, so that's that.