Argument

So recently, as I believe I've mentioned a few times, there have been a lot of people coming into our kitchen who don't live here. Mostly (OK, completely) they've been friends of the Chinese people. Now, let me just make this clear - yesterday, I complained about one guy having his friends in there and them cooking together. Even though I complained, and they made it smell horrible for an evening, this is still fine - he was with them, cooking and eating with them, there was nothing actually objectionable about what he was doing. But the other Chinese guy, Rui, is being more of a... how should I put this? A dickhead, about things. Friends of his keep coming into our kitchen, and cooking and eating, when they don't live here; I consider this that much more objectionable when Rui isn't with them. Essentially, they're just randomers using our kitchen. Today, two of them were in there, a guy and a girl, cooking a meal without Rui; Carolien, Janneke and I were sitting on the sofa watching the TV, deciding whether or not to say anything. Then the guy took my chopping board which I had left underneath my cupboard, and started using it. So I'm like:
"Hey, wait - that's my chopping board"
He apologised.
So I said, "Do either of you actually live here, by the way?"
The guy: "Oh no, I live downstairs."
Me: "Oh right... so why are you here?"
The guy: "We're revising for an exam in 2 days."
It was at this point that Janneke got up to start questioning him. Janneke is quite similar to Juliette (sporty, argumentative, Dutch? Yeah, it might as well be Juliette). And she was really going at him, saying "It's just a bit strange that you're here - why don't you cook in your own kitchen? I mean, I'm not saying it's you, but food has been going missing recently; we've had a lot of people that don't live here coming in and using the kitchen. It's just a bit strange that's all. Why don't you go and cook in your own kitchen?"
The guy's answer was "I don't want to."
Also, with Janneke's aggressive questioning, she managed to find out that Rui doesn't even live there anymore, and that he's given his key to the girl. But no one had told us that - from our point of view, we've just had a lot of random people on our floor And stuff really has been going missing recently as well. Apparently, Rui went on holiday about a month ago, and some other guy was in his flat; and that other guy was inviting his friends round. So like, there's just been this network of random people that no one knows, using up our space and utensils.
In stark contrast, a new guy has moved into Dmytro's room (who left earlier this week), and as soon as he got here, he introduced himself to us, and let us know that he was the guy living in Dmytro's room now.