You might check out Colin Hamer's argument that Israelite women were allowed to remarry with a certificate of divorce from the previous marriage. He points out that a slave woman could win her freedom if her master did not have relatins with her. Therefore it is illogical to believe that a dovirced woman could never remarry.

Colin Hamer, Marital Imagery in the Bible: An Exploration of Genesis 2: 24 and its Significance for the Understanding of New Testament Divorce and Remarriage Teaching (London: Apostolos Publishing Ltd., 2015).

The Roman context of Mark is not inconsequential, however. If he is writing his gospel based on Peter's memories, it would be there. Roman women often divorced and remarried in the late 1 st century and beyond. So the congregation in Rome would not have understood the original context.

And yes the undesigned coincidence argument is quite elegant, as well.