People keep talking about sharing as if it only refers to MMF, but it also refers to females sharing the same guy.
And I lost count of the number of times that it has been clearly stated that sharing of any kind would be completely OPTIONAL and decision based. The players choices determine what happens, so if you showed interest in things that can lead to MMF sharing, then you will likely get the OPTION, but if you did not, you are far less likely to get the OPTION for it. As I stated in a previous post we are now up to DAY 40. That means that only 40 days ago D was a sweet innocent, if somewhat spoiled little girl who knew little about sex and pretty much nothing about debauchery, so expecting MMF already is very unrealistic.
When it comes to FFM, the first female that D was with was her best friend that she grew up with, and that is a very believable start on the path to FFM because it was someone she knew for a long time and trusted. Then later when she found out that Georgina also had a thing for her father and she (D) was already seen to be attracted to her, it made sense for her to let Georgina in on the fun too. But the other men in the story have spent very little time with D and therefore have had very little time for attachments to form with them, unlike it has been with the females.
And last but not least the current who is the main protagonist? Read the games title. Dating "My" Daughter. Only F can be the one making that statement and that makes him the main protagonist, and the character that you the player are represented by. Rachel is out of the equation for that, since she is hardly ever present in the vast majority of the game. D we answer questions for, because she is the focus of the game, and she is, while not a full protagonist, can be seen as a part of the protagonists dynamics, "part of the time". In reality, we are the protagonist for BOTH of them, but for D we are in charge of her decisions, only part of the time, when she is alone, or with anyone other than F.
In most of the game, D makes most of her own decisions.
Whereas for F, we are the ones who make all of his decisions 100% of the time.