In the game if one of the girls are greyed out then it signifies that they are no longer in/never will be in a 'relationship' with the mc. They would still be friends and the story and the mission will go forward as usual sans sex scenes, with the girls helping the mc out with their respective roles..... maybe the only change would be if they end up separating with him because they aren't in a relationship with him but would still remain as friends...idk
Also no matter how much score u have with Dalia, major choices like saying the server password will result in them being greyed out but that doesn't mean they can't be friends, Daila and other girls have a major impact on the story anyway so their relationship status with the mc wouldn't change things up that much