I can try to help you, but I don't understand your question.
In the menu you can check the list of the quests and all the prerequisites necessary to trigger any event.
The virgin part you don't have to worry so much, the nurse in the hospital will always recuse vaginal sex. She only gives you her virginity through a special event that you can delay.
And the thing about locking yourself, I can only remember 2 instances of happening to me: the double twin enslavement, and the librarian wedding. You CAN alter the game files to fix something you didn't like, like you can make a girl virgin again or give yourself more time for the wedding event. You can also unlock the scenes at the main menu gallery.