What choices ? The only choices you make is in 3 routes where you cockblock yourself out of 1 girl per route. The game throws you a massive warning right before to save and make sure you choose the right 1 (that doesn't matter much since you can just load it and come back later for the scenes, though if you just go along, you'll indeed "change" the game)
I played Summertime such a long time ago, so I don't know what changed.
But at the same time that I say that I don't like Kinect novels, I thought the choices were kinda unnecessary.
Let the childhood friend's mom get fucked by a nun or fuck her yourself. You can fuck the childhood friend in the former, but not in the latter you have to keep fucking her mom.
Wanna bang your best friend's mom? Help him get a girlfriend or fuck her yourself in a weird cosplay fetish, but you wouldn't be able to fuck the mom.
It's just there to cockblock you from certain characters in a game that the only thing you do is run around to fuck all the women you encounter.
The game does warn you and you can easily reload, that's true, but it feels like they are just there for the sake of being there. Except for the choice of making the blue-haired girl trans or not. That was meaningful.