@WillLi To be honest, I think people keep reading this is because it's kind of a dumpster fire, but one people keep coming back to because the author keeps fanning the flames, so you kind of want to see how bad it can get.
As for who's worse between the FMC and MC, it really kind of depends on who you ask on that one because both sides tend to have compelling arguments. If you ask me, MC kind of fell into the whole "Let Me Be Evil" trope, since FMC kept calling him a perv and such, so he just went "Screw it, I'm a perv". You can argue that his sexual harassment towards her is a mixure of that and his own lust, with the latter being more on display while the former was the start of it all. For FMC, her behavior is because everyone's technically condoning it. No one is making a big stink about it or telling her off for acting that way, so she's pretty much going "OK, so it's fine if I'm a bitch".
I just find that most people feel that it's easier to blame the MC because, as you put it, "manga logic" - No matter what happens, if the progress is stagnant, blame the MC. It's his fault somehow, even when it isn't.
Blaming the FMC for everything is not all that common (partly due to her looks and some of the masochistic nature of the fandom), but that just means that more of her type can flouish. Others do blame her because they'll see an innocent man gone bad due to one bad bitch (which is actually common, sadly, and part of a never-ending cycle of assholes). Then there's the group who blame both of them because they're both assholes who say and do stupid shit.
But that's my two cents on this whole thing. I'm just waiting on the dad to bring in more logic to the situation. Don't let me down, author-san!