Found it. The criteria for "Enjoy" event are:
- Three or more days have passed since becoming Laura's boyfriend.
- It happens in Null's room when he wakes up.
- There is a "not present" tag that, at the very least, means Laura is not in the room with you, but it may also mean that nobody is in the room with you.
Possible reasons the event, and thus the quest, are not triggering.
- You are not Laura's boyfriend. It is possible to postpone that event when it triggers, and perhaps that is where the issue occurred. Did you get the event where Laura drags Null to his room and says she wants him to be her boyfriend? If not, you need to trigger than event. If postponed, i.e. you told Laura you didn't have time when she either texted you or asked to talk, I am unsure how to accomplish this.
- Null isn't sleeping in his room or isn't sleeping in his room alone. Are you constantly sleeping over with one of the girls or inviting girls to sleep in his bed? If this is the case, I would recommend sleeping alone in your room. Perhaps over a few nights to try to get the event to trigger.
- You did get the "Enjoy" event, but the relationship quest didn't activate. Did you get the scene where Kurt texts Null and says Laura is pacing outside your door? The one where Laura says she watches Null sleep through his window? If that event occurred, and the relationship event didn't, I don't know what could have caused it.
- Perhaps Relationship II did trigger, but it basically autocompleted because you already had the stats high enough to complete it. Look at completed quests to see exactly how far you've progressed. Since these events are complete when a certain love and trust threshold is reached, it is entirely plausible that, depending on when the quest activates, you may have already passed those thresholds. If that is the case, your issue may lie elsewhere.
- Did you alter your stats, use a trainer, a mod, or anything? If so, you may have broken your save.
I would recommend double checking completed quest to make sure where in the quest chain you are. I would talk to Laura and try to officially become her boyfriend if you postponed that event. I would sleep alone in your bed a few nights to see if that triggers the event. Beyond that, the only thing I could think of is to edit the save to reset some flags and see if you could get things moving again that way. My apologies that I could not be of more help and that it took so long to get back to you.