I am curious as to how this game works since I've heard this isn't a harem type shit. Is it something monogamous, or like do you have to choose only 1 girl and replay the game again for the others?
You are given free reign of your choices, and the longer the game progresses, the more it will come into play with whom and how you engaged. Basically you start with all 7 main girls routes open, and as you progress, you can slowly start losing routes either by missing certain story aspects due to your choices, or just due to lacking relationship points.
In Ep3 there is no real punishment yet if you aren't "perfect" and you pursue multiple girls, but the longer the updates go, the more you could lose due to pursuing everyone. Naturally in the end you'll end up only on one girl/route.