No, it's that rationality often doesn't fit the needs of the situation. You have the relationship backward. Speaking from experience, the best way to combat depression is to let go of your egocentric view of the universe.Well that's terrifying. To be human is to be utterly incapable of rationality.
On the topic of point one, what I can say is that rationality is a tool. Simplifying a bit, it follows the structure of premise, premise, conclusion. That is, we either know things to be true, or assume them to be true, then we search for what is necessarily though perhaps not obviously true based on our assumptions. This strategy works marvelously for, say, increasing the fuel efficiency of a V8 engine, or calculating the stress on a bridge truss. For matters of math and language, there's no substitute for rationality. But there are a lot of things in the world which occupy other spaces. There are things that are suprarational, those that can't be understood via rationality because they are too complex to understand. And there are things that are extrarational, things for which it would be nonsense to attempt to apply rationality. Parts of the human experience fall into each category, and perhaps some into both, even if this sounds paradoxical. I'm of the disposition that matters of emotion and mind fall into at least one of these categories. So, when I say that you have the relationship backward, what I mean is that to be rational is to be inhuman, because our core humanity isn't accessible to the rules that govern math and language. Certainly rationality is something that is part of the human experience, but it is just one part among many. On the second point, there's not a lot I can say. What I'll share is that sometimes, you're insignificant to the world, and sometimes, you're very significant. It's up to you to figure out which applies at a given time. The world is an integrated whole that you happen to be a piece of right now. We all like to atomize into me/everything else. But from the universe's perspective, you're part of everything else. I'd dig myself into a deep hole if I tried to elaborate any further, due to point one.