Old covenant law required that adultery be punished with death (Leviticus 20:15; Deuteronomy 22:22–24; John 8:1–11. There would be no option for remarriage if an adulterous affair was in view. Possibly the law stipulated the greatest punishment that a transgression required, rather than the only one (King David). In other instances of sexual crimes, a monetary fine was imposed (Deuteronomy 22:13–30). Given the fact that the Israelites were not free to enforce the death penalty in the time when Jesus ministered on earth (see John 18:31), a monetary fine was even more likely.
32 But I say to you that everyone who divorces his wife, except on the ground of sexual immorality, makes her commit adultery, and whoever marries a divorced woman commits adultery.