Yeah, that's a natural reaction, too. But the situation is different as it is; boundaries being pushed every day, than it would be if she was acting like a normal girl, then sharing herself cheating on her bf while drunk, and him confronting her about it. There's a buildup to it, and the MC is willingly blind about it.
I understand there're conflicting emotions for Polly here; the mixture of feeling betrayed and emboldened, doubling down on it "not being a big deal" is another method of running away, and in a way, mimics what Anna did with her bf. Psyching herself up by saying all men cheat, and that he was a douchebag anyways, just so she could feel allowed to do it herself, lessening the guilt of it all by placing it on someone else.
But that way of doing it is also very "Polly like". By reading the messages, you understand she's the type of girl to bend the rules as much as possible, and breaking them if she feels like she could get away with it, without either feeling bad about it. The "No Rules" tattoo is as clear a message as it could ever get. She's beeing crawling in that obvious direction while probing MC as well.
Normally I don't care about the writing in a porn game, but this particular story was pretty well written; it felt very humanly believable from the core characters here. What I wanted to say is that people here saying that it went from 0 to 100 and that the current ending was too rushed or artificial are not catching the human subtleties in the character and personality of everyone involved in the story. So kudos to you, mate.
There's just a pet peeve I have with MC's reaction to it all. It's either one extreme or the other. He breaks up with Polly, no ifs or buts, or accepts being a cuck. It's too compromising, imho. As a player, I would've liked to get past that part without either ending the story or jerking off to the girlfriend saying how Chad Thundercock fucks her better than me. I'm not one to self insert as the main character (main reason why I enjoy NTR without liking that idea irl), but I also don't really enjoy stories in which the MC can only be the little bitch. At least with other characters, like the goth girl (I don't remember her name off the top of my head) offer more branching possibilities.
