Read through the whole sequence(update, I mean). Meh.
How to mess everything up with one update.
Leon is the mole, his "dead" daddy is the one pulling the strings/helping him.
Unless the developer decides to put out Deus Ex Machinas here and there.
The reader, who can figure 2+2, got all of the questions answered in here and first act is not even finished yet.
I'm not Shakespeare of any sorts, but how to take susceptions of peeps off of Leon, but get him to be the one who Clara cheats with?
Give her an impossible task of sorts, alongside Leon. No? Okay, she's drunk, right? Get her to come to Leon, who's also drunk and upset of something(friend's death, I dunno) instead of him coming to her. Let them get drunk together and things to spiral out.
But nah, Leon conveniently comes to her right away)
I get it, it's NSFW VN, not great tragedy. But if you build it up with putting emphasis on a story - you've gotta do something differently.
Guess what will happen from now on? Leon will get to grope Clara here and there in front of Alan, kissing and shit with "Sorry, I couldn't hold myself off" with signs of blackmail.
So, instead of story-driven stuff with plot twists and mystery(yup, it would've still been Leon in the end, but with characters having "Red Herring" roles). We've got typical NTR story instead. Disappointed.