I gotta say, the cheating route in Pineapple Express was much better done than here. In PE, it was "explained" by MC being a hypocrite (fooling around with Cordell's sister while constantly watching over Julia x Cordell, a.k.a. being a cheating asshole). In this game, Emma just needed to get horny enough to where she desired Martin more. All you have to do is be passive enough to let them spend time together, and voila, Emma is happily cheating on you.
IDK, but it doesn't have that same effect that the cheating in PE had. I guess the element of pretending that was in PE made for a fantastic NTR experience - always wondering if Julia x Cordell were still pretending, or where they fucking for real - but in this game, you just have a slut wife that cheats because she was left alone with another man for 3 days.