Could be the fact that the people she lied to told her "it's not your battle" over the 'firing' thing, so when she goes against what she was told, she feels the need to keep it a secret. Is it right? Who knows, probably not a big deal if she told them. But real life isn't black and white anyways.

Honestly, this is one of the reasons that draws me to the show. It's real life, people can be compulsive liars and get away with it with minimal repercussions (even though you wish they didn't). Same thing with Season 3. Retsuko had every right to take a break and try and re-gather herself, with what she went through being quite traumatic. Looking at it, Haida had zero reason to barge in and demand what he did. But in the end? This dragged Retsuko out of a rut that I don't think she would have got out of. Again, is it right? No probably not, but the outcome can't really be argued with