Geez, someone stop my pedantic reflex ... I like your contrast of DMD from becoming a harem vs "poly" situation because that makes some intuitive sense.
Admittedly, I think it feels more like a swinging path because polyamory is typically about people who have intermingled, shared relationships that are meant to be more than just sex.
Thus far, D and the MC are a couple, Olivia and her father are a couple and everyone else is more or less single, but D and MC aren't showing signs (yet) of expanding their relationship to include other people ... more like expanding their sex lives to include other people. Plus, we now have a clear direction of D and the MC driving towards an exclusive marriage, presumably retaining their growth into a swinging sex lifestyle on the side.
It's always possible that Chapter 4 will lead to revelations of a bigger group within the core relationship than we are seeing now - I mean, how many times has the idea of Elena living with them been brought up? - but current indications don't feel that way to me. Yet. The notion of Elena and Jennifer feeling in love with the MC makes me wonder what's in store beyond infatuation for them. Guess we'll see.
