'Unfaithfulness' in the Bible

Indeed, the Israelite men have taken some of their daughters as wives for themselves and their sons, so that the holy seed has become mixed with the surrounding peoples. The leaders and officials have taken the lead in this unfaithfulness!”

Everyone who trembled at the words of the God of Israel gathered around me, because of the unfaithfulness of the exiles, while I sat devastated until the evening offering.

Ezra then went from the house of God and walked to the chamber of Jehohanan son of Eliashib, where he spent the night. He did not eat food or drink water, because he was mourning over the unfaithfulness of the exiles.