They are separate paths and the "cheating" is actual cheating, so not done under a shared/consensual premise (spoiler just in case...) There's a sharing path, which involves both cuck (MMC not involved, sometimes with options for MMC to be caged or for him to clean up creampies/do cum kisses) and sharing (MMC involved in an MMF threesome) and there's also a cheating path, where it's all 100% behind MMC's back. In the cheating path, there's a separation ending as MMC eventually catches them in the act, punches the other guy, and leaves. This was right at the end and there isn't really much shown afterwards - you see MMC alone, but I don't recall if it shows what happens with FMC (i.e., whether she is also alone or whether she shacks up with the other guy). On the cheating path there is also still sex with the MMC, although it might not happen as frequently once FMC gets deeper into her cheating relationship/s (it's been a while, so I can't remember it clearly enough!).