To be fair, most characters will leave - less obvious - plotholes or hanging references if not dated. As an example I mentioned in my review how when not dating Tracy the comments about Usher's song (referring on how an usher disturbed your date) don't make sense. Amanda says some strange things when you did not get Erica's BJ with her watching. Of course that is way more subtle since you just think a line of dialogue doesn't make sense, which is par for the course for the MC, instead of having sex with somebody you don't have sex with (people tend to notice such things).
The "full harem" certainly seems like the idea the author is going for, with exclusions optional but not the focus.