Well, monogamy is purely a societal thing, and the girls specifically came to the community to get away from society, so I wouldn't expect them to have socially normal attitudes about everything. With the community being its own little world apart from the wider world, it wouldn't be unrealistic for them to be different. I mean, look at Emily and Sallie, that's definitely not a normal mother-daughter relationship.
So it won't be possible not to upset them? That's a shame. I kind of figured that they were all expecting polyamory, I mean wasn't Hollie trying to set us up with the other girls herself? Or am I misremembering?
The game is currently geared towards the NPCs having 'damaged' attitudes towards relationships. None look to be particularly open to poly relationships.
At least two of the women, Belle and Hollie, are explicitly insecure about sexual/romantic attention and potential motivation of the MC. Belle is very upfront about not wanting to intrude on Hollie and is not seeking a purely sexual relationship and while flirtatious, wary of overtures because previous suitors only wanted one thing. Hollie is very upfront about wanting someone to consider very special/be considered very special by. If I were looking for polyamory, these wouldn't be the women I look towards.
The other women are also unlikely targets. Sophie is working through a bad breakup with someone she thought was 'the one' who was caught using her. Emily seems way too jealous to consider sharing Sammie. I haven't worked with M and S much as that's not my kink and even though I can rename them, it is both really obvious what they are supposed to be and the renaming only sort of works in term of the conversation text.
So yeah, I would expect there to be upset and hurt feelings. Especially since the MC enters into the Belle relationship through lying. The player cannot tell Belle the truth if he has established any form of relationship with Hollie in the first week. There is literally no option during the date's 'answer honestly' game for that admission and Belle asks the question. Nor can the MC tell Hollie that he isn't monogamous and/or they aren't exclusive during 'the talk' they have that evolves their relationship.
Now since the community seems to be a place of healing, it is possible 'healing' in the game could consist of letting go of jealousy and insecurity enough to enjoy a more open and communal sexual life. But, certainly that is not where we start. And if the game did go down the communal path, I would expect other males to be allowed in and everyone knows how well NTR and anything that looks like sharing gets accepted around these parts. I can imagine the howling already. The potential player base needs that sort of healing first.