WARNING, A LOT OF TEXT:
For me, the whole problem with this plot lies with Mary and her excessive sexual desire (which I already forgot if she actually told Satoshi about, or if she even intended to discuss it with him. Maybe they would have reached an understanding or just ended things. Satoshi is guilty of being super dense and shy when it comes to exploring new experiences (but it’s mentioned in the story that although Mary said Satoshi wasn’t interested, he DID make an effort to accompany her in those activities, even if he was terrible at them). We know that Kendo doesn’t care about anything except his own satisfaction (in sex, he does satisfy his girls without fail). He’s also super endowed, there’s no competition, and Mary succumbed at the FIRST opportunity presented to her with Chad Kendo. Ridiculously, she tried to make Satoshi (who is super dense and shy) realize what was happening and prolonged the deceit to the point where she was already corrupted and continued playing mind games with Satoshi instead of simply ending the relationship before reaching that critical point. Conclusion of villainy: Mary -> Arato (asshole) -> Kendo -> Satoshi -> Shizuka -> NPC
The only thing I would like is for there to be a third option (we don’t know what the second option is) where Satoshi, upon seeing that Mary is a lost cause and there’s no chance left, withdraws with the little dignity he has left. He doesn’t plan revenge or anything, just indifference upon no longer seeing any traces of love in Mary. He should proceed to ignore her, clear his mind, pack his things, and rebuild his life with someone else (after all, the story here is about MC Kendo). I’m just saying. (They already gave Satoshi a hard time). And by the way, Kendo should take Shizuka away from Arato (he deserves it) since I don’t see Shizuka with Satoshi due to having tendencies similar to Mary’s or worse, as she’s with anyone and Mary “seems” to only be with Kendo (in her route).