IMO the sharing route runs the risk of turning D into a porn game trope.
D experiencing new sexual adventures is the goal of sharing D, but not so much that every update has the plot of a 1970's porn movie. While fans on the sharing route want to couple D with multiple partners, many still want the quality of the story to continue. DMD would loose it's appeal if all it turned into was D meeting a character(s) who only had to say was "Yo bitch let's fuck." and D was having some sort of sex.
Chapter 4 may become challenging for the writers to balance D's obvious love of sex with a compelling story line.
Personally I like D's dreams at the start of an update to lay the ground work for what's to come.