Gracie plays people around her for various reasons so far known only to herself.
If I remember correctly, she was "angry" about Isabel occupying most of Antonio's time, leaving nothing for Gracie. While this isn't exactly sharing, the truth is that Antonio has also almost completely neglected his wife by now, too.
My point was not this, Gracie dont see humans as ... well, humans. She she humans something to posses in a way, so she dont care if he sees her wife or not, she sees as now Isabelle have Antonio, therefore she is not a good person. (I wont say hate, because that was due to cheating part)
Somewhere in this mission, MC asks "How we can continue if Antonio still around you, our social education thing" question and Gracie replies "Yeah you are right, that makes his existance abundant" -or something like that, I cant remember exactly- and then accept apology from Isabelle She is extremely possessive and hates sharing what is valuable to her.
I'm starting to remember that she was aware about the little sharade that locked them together into a closed space without an option to leave and played along despite of it.
This kind of suggests that she was expecting something like this to happen and approved it.
She explained it as "I have noticed yourfirst and second decoy plans but I couldnt see the end result, without an end result or ace in the hole, whole plan was pointless like making an excellent meal than leaving it to cool too much So I played along" and threaten MC Most probably she understood about camera/audio thing.
I dont think Gracie cares about maturity by the way, she is learning friendship from books, how can she know about maturity? She even thought holding hands in public is something shamefull, "testing about putting his thing to every hole" is something I wouldnt expect from Gracie, at least for now, because she dont have clue about any social interactions or anything social.
