The difference between these two perspectives is approaching this game as though it's a serious piece of writing whose purpose is to tell a story vs. approaching it almost-or-entirely as a vehicle for sex-fantasy. I'd say this game much more often leans in the latter direction so it's not unreasonable on its face to generally be okay with Anno's behavior but not want to explicitly see it - after all, if you see scenes like this purely as wank material then it's only natural to think I don't like content where the characters sleep around on me so why are you showing me this? If you switch gears then sure, that's Anno being Anno, and there's no narrative reason why Captain Steele should be the only one going on shore leave and the TiTS setting is very libertine &c but I can see why someone might view that as an obnoxious "you've been cucked btw" notice and not much else.
i don't think it would be so terrible to gate notices like that behind a conversation with her about her recent exploits instead of having them pop up automatically.
this is a game where everything fucks everything else and STDs just give you bigger tits when you have a sniffle. i think that was well established when you encounter native fauna on an uncharted planet and all they wanted to do was a little cotch bumping
in a world like this, there's a dog woman. she invites you into her open relationship with her actual long-term girlfriend, who she happily lets you fuck. honestly anyone dense enough to not expect said woman to sleep around should perhaps worry more about their star-shredding gravity field and its impact on their friends and family instead of stumbling upon some 2 sentences long text based """Nice Time for Roo""" throwing cold water on their crotch fiddling session.