Best book I've ever read on the privilege and joy of God's gift and/or time of singleness. Excellent biblical exposition, insightful illustrations from classical literature from St Augustine and John Milton to C.S. Lewis, George MacDonald, and J.R.R. Tolkien, and many more.
One of my favorite parts is the exposition of Isaiah 54:1 on pages 133-134.
Carolyn includes many honest personal testimonies from her own journey to contentment and enthusiastic service as a single. Yes, she still struggles at times, she admits, but continually hands her life over to the Lord's will, as we all must, no matter what arena of life we're in.
(Website linked to title.)