Darnell frequently walks his dog past the MC's house and lets it shit in your front yard. He's already targeting your sis- Tiffany for whatever mind control drug shit he's mixed up in, and he started focusing on you mo- Mary when she yelled at him for the last time his dog shit on their lawn. So he has a vested interest in peeping into your house, particularly because you seem to be inoculating the women you sleep with against whatever shit he and the principal are using to make women into sex slaves, and he's noticed this peculiarity. Ostensibly, he's tried to drug at least Becca.
Mia is the one drugging the girls, no? He's a low level pusher, and he's so shit he needs to borrow his sister's cash. I'm not sure Darnell is in the know about what's going on.
If you were running an operation like this, would you trust a dumb ass punk like Darnell? There are a few hints that he hasn't even slept with your TIFFANY yet, which would be an amazing feat if he had access to the drug. If Harry needs time to obtain the bimbo pills, hows Darnell gonna get the mind control stuff?
I also theorize that Shapiffany is inoculated by years of proximity or by somehow getting mc's cum in her. Darnell implies that he hasn't fucked Sitiffany when talking about using the remote on the mom. Her Alexis Starr account seems like a solo account. She could be wearing a shorter skirt cuz she's an exhibitionist.
I got enough theories to never have to worry about ntr in this game. And if you think it's being willfully ignorant, I can always change the script to add her inner monolog saying so. The devs are providing the tools to masterbate, what we read is up to us.