Some hints for people trying to get all the different endings.
The John's one is the "standard", so you should see that one normally.
If you want to see Marie's one, it's crucial the first part of the game: be kind with her and never leave her alone for John or someone else (like in the armwrestling scene, or in the party one).
If you want to see Lora's one instead, the most important part is after you get injured. Let her carry you to your cabin, and when you divide from Marie in chapter 6, try to stay with her the whole day.