Genesis 25:1, Who Was Abraham's Second Wife?

Then again Abraham took a wife, and her name was Keturah.

//After Sarah died, Abraham married again, to a woman named Keturah. Together, they had several more children. 1 Chronicles 1:32, however, calls Keturah not a wife but a concubine. So which is it? Wife or concubine?

Answer: Maybe both. Keturah was Sarah's maidservant and bore a child to Abraham years before she became Abraham's wife. How do we know this? Because if oral tradition is to be trusted, we already know this woman well. Keturah is another name for Hagar, the woman who bore Ishmael. The woman whom Sarah demanded be cast out into the desert with her son. Keturah means "perfumed," and the tradition notes that Hagar was "perfumed with good deeds."

So with Hagar out on her own, how did this reconnect with Abraham transpire? Well, it turns out that Isaac had been living in Beerlahairoi before he married, which hints that he had been living with Hagar and Ishmael. See Genesis 16:14, 24:62, 25:11. Evidently, after Sarah died, the influence of Isaac and Ishmael brought Hagar and Abraham back together ... one happy family once again. When Abraham died, Isaac and Ishmael together buried him.

A speculative scenario, but a pleasant one.