NTS turned NTR
Nedd help finding this one doujin i read a while back on nhentai, might have been removed. It was a short series, only 1 part. The girl had long black hair iirc, it might be a ratatatat74 one since it seems like sonething they'd write. It was about a guy who got his girl to cuck him, and as she was getting fucked she was insulting him and talking up the other guy, normal stuff. Then theres a point where she says sonething along the lines of "but its okay honey, this is all an act. I'm just roleplaying for you... is that what you thought I'd say?" Then she completely switches and starts fucking the other guy seriously, flipping off her boyfriend and degrading him, telling him he fucked up by asking to be cucked and saying she's leaving him for the bull. ITS NOT NEUTRAL ACTOR. Its a similar premise but its not the same.