Choices matter a lot in this game.
There are events where you have to decide for or against certain characters which can temporarily or permanently lock you out of progressing with one of them. You will not get all the girls in the same run if that's what you were going for (unless the devs add the harem route later on).
However the official walkthrough and guide really help if you try to complete all the routes. The game lets you skip over chapters you have already seen which makes it much easier to follow a certain route if you choose so.
If you not only want to get all the H-scenes but also understand what is going on behind the scenes you will have to play multiple runs.
Hope this answers your question and you will still give the game a try. It's great.