Well walkthrough is something of a play guide for the VN. If we somehow go to a wrong path or like when we choose a option and because of it the future options will get affected. For example if I choose angry and tough at first, the mc's charm will be low because of it during the car ride to the institution there won't be that many options left to choose (only two ig)..... If this doesn't help, you can see Eternum's walkthrough.