From Day 12, choosing to give girls the drug corrupts them.
Following the Tasks in the Journal leads you to corrupting the Nuns, University Girls, etc.
For the time being (v 0.8.1 and earlier) there's not really a way out of doing that. It is planned to give players on the "good" path a choice later on. The game still has a ton of content planned. Even if we hit v 1.0, it's not the end.