Quick list of endings and their requirements, in order of priority (higher ones will come first):
1. Harem – Sex > 95, Joy > 80, Reputation > 50
2. Lab Girl – Sex > 80, Knowledge > 90, Reputation > 40
3. Talented Bride – Sex > 80, Behavior > 75, Reputation > 30
4. Nun – Sex > 50, Morality > 60
5. Wonderful Bride – Sex >40, Behavior > 40, Morality > 40, Joy > 40
6. Office Girl – Sex > 80, Knowledge > 60
7. Brothel – Sex > 80, Morality < 10
8. Whore – Sex > 50, Behavior < 40
9. Transfer Student – Sex > 75
10. Good School – Sex < 50, Behavior > 85
11. Ashamed – Joy < 20, Reputation < 20
12. Father’s Objection – Reputation < 10
13. Return to Normal
I think, just looking at the code provided, that the last ending may never show up. There doesn't seem to be a call for it.