Why does God allow unbearable pain that doesn't go away, and can we understand it in this life?

Can we understand this in this life? Probably not. It's a concession of the Church to say, look, we know you're suffering. We can't do anything about it. And the one reason we don't understand is because this life is so short compared to the next life, where you will live for eternity. There you're going to say, well, I'm glad I used that suffering to make my life in eternity that much better, because I'll have it for all eternity for the little suffering that I endured on earth. Use it to your advantage. And not only in heaven: you will receive graces on earth. You will come very close to God in suffering. That's the reason why we fast. Because we suffer when we fast, don't we? Yeah, there's pain down there and it doesn't go away. And if nothing else brings you closer to God and makes you swallow your pride, it's fasting. That's why the Church recommends it. You can say prayers anytime. We could all say the Our Father right now, and we mean what we say. We're not being foolish here. But they're just words. I still don't do it sometimes like I should, but it's still easy. It's hard to fast. Even going without one meal per day pummels you. And by the end of that day, you're going to feel it, and you're going to be a different person, because you fasted under pain. That's how you break down the human soul that goes against the spirit. You want to break it down real fast, then fast. And of course that principle is only multiplied for people that are, as she says, in unbearable pain that's not going away.