Played through the game for several hours trying to get all the endings, but I couldn't figure out how to manage that stress level properly, so I kinda gave up on going for 100 percent completion. (haha)
Some of the endings are pretty obscure and you have to do some very specific things to reach them haha ;; I think her stress stat shouldn't be too hard to manage if you focus on getting in down in the first couple of days! It should be easier to deal with then!
I see. The problem I had was that it started off higher than the other stats, so I couldn't figure out a way to properly manage it, or even get any of the other stats to 100 before the two weeks ended.
If you sleep and take her to the cafe during the first couple of days, it should make managing her stats easier for the rest of the game. I hope this helps!