People have asked the harem question a lot, and my answer is basically that it's a harem game, until you get to a point that a girl expects a monogamous commitment. For some girls that may be relatively early in the game, and for some it may be closer to the end. Some girls will be okay with an open relationship of some kind, and some won't. There's a tease to that effect in the next update, for one of the girls.
But, there's also the possibility that you could have an all-corruption playthrough, ending with a harem of girls that are motivated to be with you due to the promise of wealth, power, or simple security.
I try to keep the game, and the personalities of the girls, rooted in some kind of reality. So I just can't see a future where like.. Gabby and Madison are willing to share you, while making it consistent with their personalities. It'd just break the reality of the game. But, I do have certain girl combos planned, and there's one girl who's polyamorous and will be cool with you dating other people.