Because being faithful is personal treat not some kind of exchange marker. If you become unfaithful just because you think someone is cheating you that means as a treat you were unfaithful without having a chance to show it.
Hummm usualy, in a ''casual'' relationship, you're equal with your partner.
But remember, you date your own daughter... Its not a realistic situation.
so, if you want this kind of road, you have it. Nobody cant judge you for your taste. DMD official will end soon and you have a looooot of contents with the MC until now.
Now:
1) This game propose us a multipath road.
2) Some players ( like me), with others tastes, want to share D with other men.
3) The story remain with somes unfinished plots ( the judge, the doc, the security guards etc).
4) the dmd ''what if'' project will come to explore these roads.
Everyone will be satisfied.