I actually hope MC manages to mostly solve this one on his own with Hanako's help. Whilst she is undisputedly the best person, as the rest of them seem to all just want in his pants to steal his wallet, if she just keeps saving his ass like Superman does to Lois Lane, it will get pretty stale. I will say I think the pacing is a bit messed up, like I don't think Hanako should have fallen for him this quickly, but I think Satomoe needs his time to shine. (He evens mentions it with the ominous "a vulnerable airhead..." quote, which might imply this is his imagination, but I doubt it)
I also want to say that this shift in tone isn't nearly as bad as other manga like Gal Cleaning, and has been built up more than in that.
compensated dating and sexual exploitation have been addressed to some extent already, and it's made very clear most of the girls want to harass and bully MC using their bodies to get blackmail over him. Hell, Takae thinks the best way to flirt with the man she's repeatedly tried to blackmail and use for her own ends is to say that the one person she wouldn't mind getting paid to date someone would be him. (I have issues with how Takae still hasn't even apologized or acknowledged what she did was wrong, which I think should either be a major point of contention in their relationship or should be at least pointed out at some point.)
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I'm a fan of grimdark universes like Warhammer 40k. Most of the shit you listed off would be LESS extreme then some of the shit you listed off. Hell, to me those conflicts are pretty standard. Dark is when you have to fight off a race of space pirates who have to instill intense emotions in their victims, lest their very souls be feed to daemonic entities slowly. And that's just the Dark Eldar, Chaos is its own bag of existential horror...
What I'm trying to say is that I am almost certainly a terrible person who is desensitized to all except the most extreme of fucked up shit.
@Hitspark