Hi! Thank you for your support!
To open the Christine and tentacle scenes, you have to call Michael before you even break up and he asks you to find Christine's. You will have to come to the courtyard in the evening (I don't remember the exact time 19:00 or 20:00) and there will be a scene with Christina , after that you will have to talk to Christina in the canteen and then you can get the monster scene.