Only RPG maker game that I remember I saw where MC who got ruined, actually came back as a Demon Lord and destroyed everybody including the whore girls that got stolen from him in the ending. But, I can't remember what the name of the game I saw it ages ago. All I remember about it's plot was that it was about some kind of Adventurer Guild that ruined MC and corrupted his Childhood Sweetheart.
I think Thug Hero Party has a plot something like that, but I found the game too depressing to play all the way through (and the gallery mode glitched out when I tried to just view the scenes from it). Also, it's not an adventurer guild, but rather the gang the "Hero" leads (more specifically, the "Hero" corrupts MC's girlfriend, his sister and some other women get raped and corrupted by other members of the party, and the lesser members of the gang get to fuck them once they've been broken in).
For some others, NTRPG2 has the main character go a little nuts at the end and kill one of the minor lackeys of the villain, but then gets stabbed by said lackey's lover and dies. The Henteria Chronicles games generally have a "Good" ending (girls have all had their brains fucked out by the villains, but the MC gets them in the end), an NTR ending, and a True Ending; starting with number 2 there's also a Revenge ending that's more like what you're mentioning here (although more "MC keeps the girls as sex-slaves" than "MC destroys the world"). Henteria Chronicles however is pretty much an Oblivious MC setting, with him not discovering what's going on until very near the end.
As for here, one reason MC won't go on a murdering spree is that he's not a goddamn sociopath. There's also a significant power disparity in play - the nobleman who is probably going to be the NTR villain has a lot of political connections, is a powerful combatant, and has helped the party out quite a great deal. I don't know what route the author is going to go with things, but possibilities could include the girls doing the villain(s) sexual favors to help MC. There's also the added wrench of the Entity from the most recent update - MC might not know what's real, might be seeing things from a place and time where he can't do anything, be frozen in place as things play out, etc.