You'd figure after a year or so the effects of the past would have worn off by now. I guess it never goes away, especially when it's without help. A single word is all it takes to start a spiral, and a couple is all he needs to start getting better, help is an effort and he can't do it alone, and thank god he isn't alone. Though... are you sure it was something she said? Or Someone or something triggers Midoriya's depression, and Aizawa hears his call.