Responses
It's mostly stress. Yota is at the age when japanese people are finishing college and are looking for jobs. There's a season for that, when many japanese young man and woman are in black suits all over the place. It's intense.
They get stressed because they understand a stable job as "the shackles of freedom"
(Of course I'm generalizing here, it's just a rough cultural explanation. And a hypothesis)
Ohh that's a good hypothesis!
Hope someday an actual explanation of why they suddenly have ED in their twenties appears on those types of mangas... Only reason I have seen is the "women traumatized me :(("