the other day she left and did't come home until late morning/early afternoon the next day, so it's possible she stayed with him...That's just my opinion though, she only has about a little over a week until Marco returns, so we'll see if anything further happens.
i agree with your friend, it says Marco is on vacation until the 26 of August. This is the second time i've seen this other guy at the apartment, in my opinion you can definitely tell there is something going on there. I think Stesha is trying to keep it off camera though.