The little details in this are really nice so far, I really like the stylized contents page and her phone being broken as a detail. Also Yoru's excuse for not responding is immediately sus, my headcanon right now is she's the type who gets off on worrying her partner and so she will actively neglect her to get a rise.
I agree with the conclusion but not the antecedent.
As they aren't living together or anything, a mere 28 hours of silence is perfectly acceptable and must not mean you're avoiding your partner. But really, a cold? From my experience, bed-ridden people use their phone more, not less.