She has ulterior motives that are probably up to no good. Too easy to catch upon this. The MC is fucked because he has no frame as a man to set boundaries with the HS girl.
As man, your woman should know that you're capable of picking up other women (not that you should act upon it) because that creates healthy competition. It's good that the female MC sensed dread thinking he was cheating but the male MC is too comforting too, which is no good either. That's why...
@Kaiser92 I think he's a novelist who writes crimes stories, so maybe in his research for faithfulness about murderers, he came about methods of killing and disposals. Or I'm just plain wrong.
Yugami's still not wrong though. Not with Kadota being a bootlicker and not with Nitaku being a motherfucker sociopath with everyone. BASED GOD YUGAMI! HAIL YUGAMI!