'Faithless' in the Bible
Judah has been faithless and dealt treacherously, and an abomination has been committed in Israel and in Jerusalem; for Judah [that is, Jewish men] has profaned the holy sanctuary of the Lord which He loves, and has married the daughter of a foreign god [having divorced his Jewish wife].
Yet you ask, Why does He reject it? Because the Lord was witness [to the covenant made at your marriage] between you and the wife of your youth, against whom you have dealt treacherously and to whom you were faithless. Yet she is your companion and the wife of your covenant [made by your marriage vows].
And did not God make [you and your wife] one [flesh]? Did not One make you and preserve your spirit alive? And why [did God make you two] one? Because He sought a godly offspring [from your union]. Therefore take heed to yourselves, and let no one deal treacherously and be faithless to the wife of his youth.