@Adriane, Ros will be defecting with Klaus, yeah? Even though it goes against her entire job description? XD
What Kierke said, plus her main/only motivation for what she does is her parents (and a love of language and making people happy but that's benefits) and she's about to find out some life-changing information, plus her biggest personality trait is that she follows her heart over the smarter decisions/cares more about people than work and she's also about to come to some realizations about Klaus, so when it happens it really won't be a big surprise she defects to go with Klaus and keep him safe than stay with the Nazi party.
Also I don't know if Mat and Aaron would risk living together UNLESS they found each other as roommates and then the romance started??? Just an idea
Ros might be weird about it but not extremely, simply because she would have the Nazi party disgust for homosexuality drilled into her brain, but without it she would definitely have the idea of letting people love who they love and staying out of other people's business if it doesn't concern her, plus she'd grow to like Mat and Aaron both and that would matter more than what they're doing together so she would probably just be a bit uncomfortable for a while.