Jewish marriage is intended to be for life, but it has always been accepted that sometimes things do not work out. If the marriage breaks down and divorce appears to be inevitable, the man has to give his wife a get. This is a document of divorce and has to be presented at a rabbinical court (Bet Din).
If a man marries a woman who becomes displeasing to him because he finds something indecent about her… he writes her a certificate of divorce, gives it to her and sends her from his house.Deuteronomy 24:1
The divorce then takes place after three months to make sure that the woman is not pregnant.