One of the most reliable features of a difficult emotional state is that it feels permanent. Not "I feel bad today" — more like "this is what my life is." The darkness colonises the way you see backward and forward in time. The version of you that felt okay seems very far away, and the possibility of that version returning feels theoretical at best.
This is not a personality disorder. It's just how present-tense experience works when the present tense is difficult.
Weather versus climate
The distinction that sometimes helps is between weather and climate. Weather is what's happening right now. Climate is the long-term pattern. Right now, in the middle of it, they can feel identical — but they're not the same thing.
Storm weather isn't a life sentence. It's a period of weather. The fact that you can't see past it from inside it doesn't mean there's nothing on the other side.
This is not the same as being told "it gets better," which is often unhelpful because it asks you to feel hopeful before the conditions for hope are present. It's closer to: you don't have to be better right now. You just have to be in this, without deciding it's permanent, because you can't actually know that from here.
The album title
William Cloudborn's album Storm Weather, Not a Life Sentence is built on this exact distinction. The music doesn't try to lift you out of the storm. It sits in it alongside you and keeps the word "not" in the title — just far enough away to keep the door open without forcing you through it.
That's the only move available when the weather is bad enough. You stay present, you don't decide it's permanent, and you wait.
"You don't have to feel it changing. You just have to stay while it does."
— William Cloudborn