Like i said, it'd be much better if Ann and MC had some talk about this before they all go to sleep, to bridge this.So you don't find it at all odd that if you've never shared Ann with anyone up to that point, that she just goes all out DP with two complete strangers? Just because she's sharing the bed with them? That whole setup is just... weird to me. Even inviting them in to stay is crazy. I get it... porn logic... but still. Also, there just was no build up... no excitement. It felt like a scene that was put there just to see Bobblehead get shared/fucked.
At the same time, like you note, the whole inviting guys in (and making Ann go invite them while in her underwear) is pretty outrageous, and realistically only something that'd be done by the player who does want to see Ann get fucked by those strangers. It is a porn game and we all could guess what the outcome of that would be. So, if the player chooses to invite them and then also chooses to have Ann share the bed with them (while opting to stay out himself) and then complains "but then she fucked those guys and i never saw that coming" it rings completely fake, tbh.
It honestly wouldn't surprise me if the dev largely presumed that this setup would only be picked by people who were into sharing Ann from the get-go, and so the need for any transition/warmup talk slipped their mind. There's always a possibility it'll be addressed and added in some later update, though.