Well, yeah they have been trained to be "decent ladies" (by Wilfred & Cordia), but you do know that MC is basically countering that with more and more interactions with the girls, right?
With Gracie, there's kissing (which basically evolved into tongue kissing), fondling, massaging
while watching porn), in which Gracie from previously before she met the MC (and started a "learning"
relationship) would have even considered.
With Luna, like Gracie, she's grown accustomed to MC's fondling & touching etc coming to enjoy it (and she even says "breast", which she previously thought inappropriate to say).
There's also Isabel & Cordia, but I'll skip them because otherwise I think this message will get far too long.
Musala Hills, in my eyes looked like a quiet place for most part. Sure, there might be rare times a civilian might just appear, but it's a place where Luna sets up contact with TJ (her gunsmith) to buy her illegally customized guns. So she's likely picked that spot for a reason, because she doesn't want to get caught (due to a possible civilian seeing her in the act), and towns people rarely venture there.
No place more private than that, if you ask me (unless TJ somehow manages to catch them in the act
)
Regarding rooftop for Gracie, yeah it's extent of privacy is probably lesser than Musala Hills, because it's still part of the town. But still, it's on top of the building and the exposure of the act is less likely, unless MC Gracie forget to bar the door heading up to the roof (in case, people who live in the building hear them).
With MC and girls being more and more flirty, perhaps it's just me but I wouldn't mind them getting more adventurous (even for their first time), or even a little bit risk taking or daring in terms of places where they have sex. Because as you said, just having each of them do it in the mansion and hotel comes off as.......well boring lol.
And to be honest, regarding having sex in the mansion, I'm a bit curious as to how that will be covered later on. Till now, every thing MC has done was just teasing and a bit more, but what would happen when full on acts of sex are done? Will rest of the Family just not hear (using the reasoning that this is a game, so other people can't hear what's going on) all the moaning and groanings of ecstasy?
I mean sure, I could be wrong, but even so, I do like variety and mixing things up.