Original Commentary
Originally, Kimberly was going to be sick in the last story arc, but it was pushed back... personally I prefer to think of it as a relapse.

Modern Commentary
Misunderstandings. And new relationship friction. Both of them could've handled this conversation a bit better. More patiently and more pleasantly.
But you learn where boundaries are by testing them. Relationships aren't just constant sweetness. And when it's just you, then feeling lousy is feeling lousy but missed pay isn't coming back.
Also, they just moved into a new place and extra money seldom lasts long- Terrence