In his memoir, John Newton tells about having to leave his bride. Neither of them were in Christ. As he returned to his duties of ship captain, he said that the separation was like death. But it was during that separation, that God really pulled on his heart. Through God's working during that time, they both ended up alive in Christ.
If I could have obtained my fond, short-sighted wish, and have continued with her, I see that, humanly speaking, it might have proved the ruin of us both.*
We all have those "Thank God for Unanswered Prayer" moments. When, God's best seems to break our hearts. Looking back we can nod our heads at the hard times and see how God has been faithful. But when we are facing those moments... when we are looking at the vastness ahead of us and begin to loose hope, it is then that we need to say to remind our souls:
*page 111 of Memories of the Rev. John Newton. Read the full text here.