We are not necessarily doubting that God will do the best for us; we are wondering how painful the best will turn out to be.
Sometimes the best is extremely painful, especially as we're walking through it. But I'm grateful that He works all things together for good. Yes, it's hard to see sometimes. It's something I'm wrestling with right now. But whatever you're walking through today, remember this: God is doing the best thing, even when it's hard to see.