In this pass in Ezra, it shows how the Israelite’s were forced to send away the wives they took from foreign nations and the children they had with them. This seemed cruel to me, and I wondered what other theologians though on the topic. 

A great write up is found here: http://www.evidenceunseen.com/bible-difficulties-2/ot-difficulties/ezra-job/ezra-103-doesnt-it-seem-cruel-that-these-pagan-wives-and-children-would-be-put-away-by-these-men/

“Third, this could be a case of an irresolvable moral dilemma. Dilemmas like these occur when there is no good ethical choice; that is, both options are bad. In such circumstances, it is appropriate to choose the greater good (or the lesser of two evils).

Under Solomon’s reign, the nation of Israel divided and eventually split, because Solomon’s idol-worshipping wives led him away from God. 1 Kings 11:2 states, “They [the unbelieving wives] will surely turn your heart away after their gods.” Solomon’s decision to take foreign wives led to a 500 year spiritual and moral decay in Israel, ending in child sacrifice, prostitution, and eventual judgment in the Babylonian Exile. Ezra 9-10 takes place on the eve of the Exile… and the men were instantaneously falling back into the same exact sin of King Solomon!

While divorce is immoral, having all of the men of Israel being married to idol worshippers would be even worse. Saving the nation of Israel from corporate apostasy and judgment is ethically greater than preserving several dozen marriages. Moral dilemmas like these end in poor results no matter how you pick. Either circumstance is ugly, but one is worse than the other.

Fourth, the unbelieving wives could have been given an opportunity to convert to Judaism. Nothing in OT law explicitly prohibits Jews from marrying Gentiles, as long as they converted to Judaism (e.g. Ruth and Boaz would be a key example). While Ezra 10 does not explicitly tell us the spiritual convictions of the wives, could it be that they refused to convert to Judaism in the full two months it took to decide this legal case? (Ezra 10:16-17)

Furthermore, once (or if?) these women refused to convert to Judaism, it could’ve been an ethical dilemma on what to do with the children. Presumably, these children were very young (perhaps even newborns?), and tearing the children away from their mothers would be a tragic circumstance.”

Another good site is: https://www.gotquestions.org/abandon-foreign-wives-children.html

“We know that God hates divorce (Malachi 2:16), and some have asked how this event is related to the issue of divorce in today’s society. A couple of relevant points can be considered. First, this event took place during a previous dispensation, in a time when God’s chosen people were to live according to the Law of Moses. Christians today should not look to this account for justification to divorce a spouse.

Also, 1 Corinthians 7:15–16 gives the related principle for today’s believers married to unbelievers. Paul wrote, “If the unbeliever leaves, let it be so. The brother or the sister is not bound in such circumstances; God has called us to live in peace. How do you know, wife, whether you will save your husband? Or, how do you know, husband, whether you will save your wife?” In other words, a believer is called to stay with an unbelieving spouse whenever possible. However, if the unbelieving spouse abandons the relationship, the believing spouse is not to dispute the matter.”