This is basically a romance development I would expect from an eroge romance VN, but never from a manga. I have to assume something is still gonna happen after Megu leaves (though, no saucy H-scene in an all-ages manga sadly).
So they live together for a week without letting their parents know huh..... I guess it is a bad actually, cause if their parents know the relationship can begin to crumble.
Well maybe since this is manga this kind of things seems normal, but it still a bit weird cause even though they behaviour is a good kid when live in the same roof alone well... Usually it will lead to something (aka s*x). Especially Rin initiate a 'kiss' and in 'her own room' .