i dont really get the non harem dating sim, does it mean that i can only date with 1 girl ?
non harem usually means that you can get like 1 or 2 sex scenes with every character but at some point you will have to decide which character to focus on. ie: fun to play for the first few chapters, then fall off HARD once you have to "pick." A good example of this is Leap of Faith. Fantastic game up until you have to pick one girl.
Yesn't!
In the end you can only date 1 girl yes, but you aren't punished a lot early game (and this is all still early with latest Ep4) if you are checking the other girls and their paths at the moment.
As the game progresses you'll have to slowly start focusing on one girl, as it will be harder and harder to keep highest points and paths with all girls at once ^^