Ntr/Swinger doujinshi

In the plot the main couple had problems in sex so they ask for advise to their friends and the friends offered them to exchange because the friends always get to finish, so they do that and the NTRmc had a big dick and the MC was banging the NTRmc g (boring sex, she even ends up sleeping i think), the fmc get to cum with the ntrmc and even got crempied on her even tho the mc told her to use condom, at the end we see the NTRmc telling the fm to fuck again in private but she rejects him because the main couple solved the sexual problem, she was kind of a tsundere the whole time with thr NTRmc