In Mark, 10, Jesus is asked by the Pharisees (“to test Him”) whether divorce is lawful. As He admits, the Law of Moses (Deuteronomy 24 and elsewhere) permitted divorce under some conditions. But Jesus argued more broadly, basing His words on the second chapter of Genesis, “the two will become one flesh.” Therefore, Jesus says, “what God has joined together, let not man put asunder.”
The Mosaic Law on divorce is complex, but the overriding sense is that it is at best a necessary evil caused by unnecessary (and worse) evils. (As Jesus explained, “For your hardness of heart Moses wrote you this commandment.”) Adultery and abuse were the commonly accepted justifications. Remarriage of divorced persons was permitted in some cases and prohibited in others.
Throughout the Bible, many aspects of divorce are addressed: Matthew 19:12 echoes Mark. Malachi 2:16 is strong: “For I hate divorce, says the Lord.” Luke 16:18 condemns re-marriage. Deuteronomy 24:1-4 even addresses serial divorce-and-re-marriage! But one omission is glaring: there is not a word about child custody. The impact on the children receives no more consideration than it does in a modern American courtroom, where children are an afterthought at best.