Viewing post in Love & Sex : Second Base comments
During her events of the study of the bible, you should have picked the option to question the bible and the religion. You need a certain amount on the INT stat for that.
And with that some of the following event would have either been a little different, or completely different.
Seeing you already have 85 of love, you basically lost this option. So you should first finish her romance with her full purity and marry her. To get the achievement.
Reload the game before proposing.
And then use the hypnosis skill to reduce her purity and corrupt her.
Well during the bible reunions you should have questioned her every time.
Then after finishing all the studies there are side missions if you wish to call them, that will also lower the minimum rank of her purity.
At that point you should give her romance novels as presents, each novel reduce her purity by 1.